diff --git a/public/arrays b/public/arrays
index 352a010..0a60105 100644
--- a/public/arrays
+++ b/public/arrays
@@ -206,7 +206,7 @@ typical Go. We&rsquo;ll look at slices next.</p>
     </div>
     <script>
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-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var a [5]int\u000A    fmt.Println(\"emp:\", a)\u000A');codeLines.push('    a[4] = 100\u000A    fmt.Println(\"set:\", a)\u000A    fmt.Println(\"get:\", a[4])\u000A');codeLines.push('    fmt.Println(\"len:\", len(a))\u000A');codeLines.push('    b := [5]int{1, 2, 3, 4, 5}\u000A    fmt.Println(\"dcl:\", b)\u000A');codeLines.push('    var twoD [2][3]int\u000A    for i := 0; i \x3C 2; i++ {\u000A        for j := 0; j \x3C 3; j++ {\u000A            twoD[i][j] = i + j\u000A        }\u000A    }\u000A    fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var a [5]int\u000A    fmt.Println(\"emp:\", a)\u000A');codeLines.push('    a[4] \x3D 100\u000A    fmt.Println(\"set:\", a)\u000A    fmt.Println(\"get:\", a[4])\u000A');codeLines.push('    fmt.Println(\"len:\", len(a))\u000A');codeLines.push('    b :\x3D [5]int{1, 2, 3, 4, 5}\u000A    fmt.Println(\"dcl:\", b)\u000A');codeLines.push('    var twoD [2][3]int\u000A    for i :\x3D 0; i \x3C 2; i++ {\u000A        for j :\x3D 0; j \x3C 3; j++ {\u000A            twoD[i][j] \x3D i + j\u000A        }\u000A    }\u000A    fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');
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     <script src="site.js" async></script>
   </body>
diff --git a/public/atomic-counters b/public/atomic-counters
index 2d52529..a6fef35 100644
--- a/public/atomic-counters
+++ b/public/atomic-counters
@@ -236,7 +236,7 @@ state.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"sync/atomic\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var ops uint64\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i := 0; i \x3C 50; i++ {\u000A        wg.Add(1)\u000A');codeLines.push('        go func() {\u000A            for c := 0; c \x3C 1000; c++ {\u000A');codeLines.push('                atomic.AddUint64(&ops, 1)\u000A            }\u000A            wg.Done()\u000A        }()\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A');codeLines.push('    fmt.Println(\"ops:\", ops)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"sync/atomic\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var ops uint64\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i :\x3D 0; i \x3C 50; i++ {\u000A        wg.Add(1)\u000A');codeLines.push('        go func() {\u000A            for c :\x3D 0; c \x3C 1000; c++ {\u000A');codeLines.push('                atomic.AddUint64(\x26ops, 1)\u000A            }\u000A            wg.Done()\u000A        }()\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A');codeLines.push('    fmt.Println(\"ops:\", ops)\u000A}\u000A');codeLines.push('');codeLines.push('');
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   </body>
diff --git a/public/base64-encoding b/public/base64-encoding
index 13baf61..74ffc9a 100644
--- a/public/base64-encoding
+++ b/public/base64-encoding
@@ -191,7 +191,7 @@ but they both decode to the original string as desired.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    b64 \"encoding/base64\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    data := \"abc123!?$*&()\'-=@~\"\u000A');codeLines.push('    sEnc := b64.StdEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(sEnc)\u000A');codeLines.push('    sDec, _ := b64.StdEncoding.DecodeString(sEnc)\u000A    fmt.Println(string(sDec))\u000A    fmt.Println()\u000A');codeLines.push('    uEnc := b64.URLEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(uEnc)\u000A    uDec, _ := b64.URLEncoding.DecodeString(uEnc)\u000A    fmt.Println(string(uDec))\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    b64 \"encoding/base64\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    data :\x3D \"abc123!?$*\x26()\'-\x3D@~\"\u000A');codeLines.push('    sEnc :\x3D b64.StdEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(sEnc)\u000A');codeLines.push('    sDec, _ :\x3D b64.StdEncoding.DecodeString(sEnc)\u000A    fmt.Println(string(sDec))\u000A    fmt.Println()\u000A');codeLines.push('    uEnc :\x3D b64.URLEncoding.EncodeToString([]byte(data))\u000A    fmt.Println(uEnc)\u000A    uDec, _ :\x3D b64.URLEncoding.DecodeString(uEnc)\u000A    fmt.Println(string(uDec))\u000A}\u000A');codeLines.push('');codeLines.push('');
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diff --git a/public/channel-buffering b/public/channel-buffering
index 5f2d1f5..0bea69d 100644
--- a/public/channel-buffering
+++ b/public/channel-buffering
@@ -153,7 +153,7 @@ concurrent receive.</p>
     </div>
     <script>
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-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages := make(chan string, 2)\u000A');codeLines.push('    messages \x3C- \"buffered\"\u000A    messages \x3C- \"channel\"\u000A');codeLines.push('    fmt.Println(\x3C-messages)\u000A    fmt.Println(\x3C-messages)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages :\x3D make(chan string, 2)\u000A');codeLines.push('    messages \x3C- \"buffered\"\u000A    messages \x3C- \"channel\"\u000A');codeLines.push('    fmt.Println(\x3C-messages)\u000A    fmt.Println(\x3C-messages)\u000A}\u000A');codeLines.push('');
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diff --git a/public/channel-directions b/public/channel-directions
index f79750a..2814e81 100644
--- a/public/channel-directions
+++ b/public/channel-directions
@@ -145,7 +145,7 @@ receive on this channel.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func ping(pings chan\x3C- string, msg string) {\u000A    pings \x3C- msg\u000A}\u000A');codeLines.push('func pong(pings \x3C-chan string, pongs chan\x3C- string) {\u000A    msg := \x3C-pings\u000A    pongs \x3C- msg\u000A}\u000A');codeLines.push('func main() {\u000A    pings := make(chan string, 1)\u000A    pongs := make(chan string, 1)\u000A    ping(pings, \"passed message\")\u000A    pong(pings, pongs)\u000A    fmt.Println(\x3C-pongs)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func ping(pings chan\x3C- string, msg string) {\u000A    pings \x3C- msg\u000A}\u000A');codeLines.push('func pong(pings \x3C-chan string, pongs chan\x3C- string) {\u000A    msg :\x3D \x3C-pings\u000A    pongs \x3C- msg\u000A}\u000A');codeLines.push('func main() {\u000A    pings :\x3D make(chan string, 1)\u000A    pongs :\x3D make(chan string, 1)\u000A    ping(pings, \"passed message\")\u000A    pong(pings, pongs)\u000A    fmt.Println(\x3C-pongs)\u000A}\u000A');codeLines.push('');
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     <script src="site.js" async></script>
   </body>
diff --git a/public/channel-synchronization b/public/channel-synchronization
index 71fec12..804f06c 100644
--- a/public/channel-synchronization
+++ b/public/channel-synchronization
@@ -184,7 +184,7 @@ started.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(done chan bool) {\u000A    fmt.Print(\"working...\")\u000A    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A');codeLines.push('    done \x3C- true\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    done := make(chan bool, 1)\u000A    go worker(done)\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(done chan bool) {\u000A    fmt.Print(\"working...\")\u000A    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A');codeLines.push('    done \x3C- true\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    done :\x3D make(chan bool, 1)\u000A    go worker(done)\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
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     <script src="site.js" async></script>
   </body>
diff --git a/public/channels b/public/channels
index 6ae7ade..c3f4a4a 100644
--- a/public/channels
+++ b/public/channels
@@ -168,7 +168,7 @@ message without having to use any other synchronization.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages := make(chan string)\u000A');codeLines.push('    go func() { messages \x3C- \"ping\" }()\u000A');codeLines.push('    msg := \x3C-messages\u000A    fmt.Println(msg)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    messages :\x3D make(chan string)\u000A');codeLines.push('    go func() { messages \x3C- \"ping\" }()\u000A');codeLines.push('    msg :\x3D \x3C-messages\u000A    fmt.Println(msg)\u000A}\u000A');codeLines.push('');codeLines.push('');
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   </body>
diff --git a/public/closing-channels b/public/closing-channels
index 5271faa..cba2538 100644
--- a/public/closing-channels
+++ b/public/closing-channels
@@ -194,7 +194,7 @@ example: <code>range</code> over channels.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A    jobs := make(chan int, 5)\u000A    done := make(chan bool)\u000A');codeLines.push('    go func() {\u000A        for {\u000A            j, more := \x3C-jobs\u000A            if more {\u000A                fmt.Println(\"received job\", j)\u000A            } else {\u000A                fmt.Println(\"received all jobs\")\u000A                done \x3C- true\u000A                return\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    for j := 1; j \x3C= 3; j++ {\u000A        jobs \x3C- j\u000A        fmt.Println(\"sent job\", j)\u000A    }\u000A    close(jobs)\u000A    fmt.Println(\"sent all jobs\")\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A    jobs :\x3D make(chan int, 5)\u000A    done :\x3D make(chan bool)\u000A');codeLines.push('    go func() {\u000A        for {\u000A            j, more :\x3D \x3C-jobs\u000A            if more {\u000A                fmt.Println(\"received job\", j)\u000A            } else {\u000A                fmt.Println(\"received all jobs\")\u000A                done \x3C- true\u000A                return\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    for j :\x3D 1; j \x3C\x3D 3; j++ {\u000A        jobs \x3C- j\u000A        fmt.Println(\"sent job\", j)\u000A    }\u000A    close(jobs)\u000A    fmt.Println(\"sent all jobs\")\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/closures b/public/closures
index e31c87a..3ef94ee 100644
--- a/public/closures
+++ b/public/closures
@@ -190,7 +190,7 @@ recursion.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func intSeq() func() int {\u000A    i := 0\u000A    return func() int {\u000A        i++\u000A        return i\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    nextInt := intSeq()\u000A');codeLines.push('    fmt.Println(nextInt())\u000A    fmt.Println(nextInt())\u000A    fmt.Println(nextInt())\u000A');codeLines.push('    newInts := intSeq()\u000A    fmt.Println(newInts())\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func intSeq() func() int {\u000A    i :\x3D 0\u000A    return func() int {\u000A        i++\u000A        return i\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    nextInt :\x3D intSeq()\u000A');codeLines.push('    fmt.Println(nextInt())\u000A    fmt.Println(nextInt())\u000A    fmt.Println(nextInt())\u000A');codeLines.push('    newInts :\x3D intSeq()\u000A    fmt.Println(newInts())\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
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   </body>
diff --git a/public/collection-functions b/public/collection-functions
index 33c38fd..6d7db8c 100644
--- a/public/collection-functions
+++ b/public/collection-functions
@@ -371,7 +371,7 @@ type.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func Index(vs []string, t string) int {\u000A    for i, v := range vs {\u000A        if v == t {\u000A            return i\u000A        }\u000A    }\u000A    return -1\u000A}\u000A');codeLines.push('func Include(vs []string, t string) bool {\u000A    return Index(vs, t) \x3E= 0\u000A}\u000A');codeLines.push('func Any(vs []string, f func(string) bool) bool {\u000A    for _, v := range vs {\u000A        if f(v) {\u000A            return true\u000A        }\u000A    }\u000A    return false\u000A}\u000A');codeLines.push('func All(vs []string, f func(string) bool) bool {\u000A    for _, v := range vs {\u000A        if !f(v) {\u000A            return false\u000A        }\u000A    }\u000A    return true\u000A}\u000A');codeLines.push('func Filter(vs []string, f func(string) bool) []string {\u000A    vsf := make([]string, 0)\u000A    for _, v := range vs {\u000A        if f(v) {\u000A            vsf = append(vsf, v)\u000A        }\u000A    }\u000A    return vsf\u000A}\u000A');codeLines.push('func Map(vs []string, f func(string) string) []string {\u000A    vsm := make([]string, len(vs))\u000A    for i, v := range vs {\u000A        vsm[i] = f(v)\u000A    }\u000A    return vsm\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var strs = []string{\"peach\", \"apple\", \"pear\", \"plum\"}\u000A');codeLines.push('    fmt.Println(Index(strs, \"pear\"))\u000A');codeLines.push('    fmt.Println(Include(strs, \"grape\"))\u000A');codeLines.push('    fmt.Println(Any(strs, func(v string) bool {\u000A        return strings.HasPrefix(v, \"p\")\u000A    }))\u000A');codeLines.push('    fmt.Println(All(strs, func(v string) bool {\u000A        return strings.HasPrefix(v, \"p\")\u000A    }))\u000A');codeLines.push('    fmt.Println(Filter(strs, func(v string) bool {\u000A        return strings.Contains(v, \"e\")\u000A    }))\u000A');codeLines.push('    fmt.Println(Map(strs, strings.ToUpper))\u000A');codeLines.push('}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func Index(vs []string, t string) int {\u000A    for i, v :\x3D range vs {\u000A        if v \x3D\x3D t {\u000A            return i\u000A        }\u000A    }\u000A    return -1\u000A}\u000A');codeLines.push('func Include(vs []string, t string) bool {\u000A    return Index(vs, t) \x3E\x3D 0\u000A}\u000A');codeLines.push('func Any(vs []string, f func(string) bool) bool {\u000A    for _, v :\x3D range vs {\u000A        if f(v) {\u000A            return true\u000A        }\u000A    }\u000A    return false\u000A}\u000A');codeLines.push('func All(vs []string, f func(string) bool) bool {\u000A    for _, v :\x3D range vs {\u000A        if !f(v) {\u000A            return false\u000A        }\u000A    }\u000A    return true\u000A}\u000A');codeLines.push('func Filter(vs []string, f func(string) bool) []string {\u000A    vsf :\x3D make([]string, 0)\u000A    for _, v :\x3D range vs {\u000A        if f(v) {\u000A            vsf \x3D append(vsf, v)\u000A        }\u000A    }\u000A    return vsf\u000A}\u000A');codeLines.push('func Map(vs []string, f func(string) string) []string {\u000A    vsm :\x3D make([]string, len(vs))\u000A    for i, v :\x3D range vs {\u000A        vsm[i] \x3D f(v)\u000A    }\u000A    return vsm\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var strs \x3D []string{\"peach\", \"apple\", \"pear\", \"plum\"}\u000A');codeLines.push('    fmt.Println(Index(strs, \"pear\"))\u000A');codeLines.push('    fmt.Println(Include(strs, \"grape\"))\u000A');codeLines.push('    fmt.Println(Any(strs, func(v string) bool {\u000A        return strings.HasPrefix(v, \"p\")\u000A    }))\u000A');codeLines.push('    fmt.Println(All(strs, func(v string) bool {\u000A        return strings.HasPrefix(v, \"p\")\u000A    }))\u000A');codeLines.push('    fmt.Println(Filter(strs, func(v string) bool {\u000A        return strings.Contains(v, \"e\")\u000A    }))\u000A');codeLines.push('    fmt.Println(Map(strs, strings.ToUpper))\u000A');codeLines.push('}\u000A');codeLines.push('');
     </script>
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diff --git a/public/command-line-arguments b/public/command-line-arguments
index 687aefd..a3f61e4 100644
--- a/public/command-line-arguments
+++ b/public/command-line-arguments
@@ -170,7 +170,7 @@ with flags.</p>
     </div>
     <script>
       var codeLines = [];
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+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    argsWithProg :\x3D os.Args\u000A    argsWithoutProg :\x3D os.Args[1:]\u000A');codeLines.push('    arg :\x3D os.Args[3]\u000A');codeLines.push('    fmt.Println(argsWithProg)\u000A    fmt.Println(argsWithoutProg)\u000A    fmt.Println(arg)\u000A}\u000A');codeLines.push('');codeLines.push('');
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   </body>
diff --git a/public/command-line-flags b/public/command-line-flags
index 024349f..b308844 100644
--- a/public/command-line-flags
+++ b/public/command-line-flags
@@ -310,7 +310,7 @@ and show the help text again.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"flag\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    wordPtr := flag.String(\"word\", \"foo\", \"a string\")\u000A');codeLines.push('    numbPtr := flag.Int(\"numb\", 42, \"an int\")\u000A    boolPtr := flag.Bool(\"fork\", false, \"a bool\")\u000A');codeLines.push('    var svar string\u000A    flag.StringVar(&svar, \"svar\", \"bar\", \"a string var\")\u000A');codeLines.push('    flag.Parse()\u000A');codeLines.push('    fmt.Println(\"word:\", *wordPtr)\u000A    fmt.Println(\"numb:\", *numbPtr)\u000A    fmt.Println(\"fork:\", *boolPtr)\u000A    fmt.Println(\"svar:\", svar)\u000A    fmt.Println(\"tail:\", flag.Args())\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"flag\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    wordPtr :\x3D flag.String(\"word\", \"foo\", \"a string\")\u000A');codeLines.push('    numbPtr :\x3D flag.Int(\"numb\", 42, \"an int\")\u000A    boolPtr :\x3D flag.Bool(\"fork\", false, \"a bool\")\u000A');codeLines.push('    var svar string\u000A    flag.StringVar(\x26svar, \"svar\", \"bar\", \"a string var\")\u000A');codeLines.push('    flag.Parse()\u000A');codeLines.push('    fmt.Println(\"word:\", *wordPtr)\u000A    fmt.Println(\"numb:\", *numbPtr)\u000A    fmt.Println(\"fork:\", *boolPtr)\u000A    fmt.Println(\"svar:\", svar)\u000A    fmt.Println(\"tail:\", flag.Args())\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/command-line-subcommands b/public/command-line-subcommands
index 6bee74c..60e9928 100644
--- a/public/command-line-subcommands
+++ b/public/command-line-subcommands
@@ -263,7 +263,7 @@ way to parameterize programs.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"flag\"\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fooCmd := flag.NewFlagSet(\"foo\", flag.ExitOnError)\u000A    fooEnable := fooCmd.Bool(\"enable\", false, \"enable\")\u000A    fooName := fooCmd.String(\"name\", \"\", \"name\")\u000A');codeLines.push('    barCmd := flag.NewFlagSet(\"bar\", flag.ExitOnError)\u000A    barLevel := barCmd.Int(\"level\", 0, \"level\")\u000A');codeLines.push('    if len(os.Args) \x3C 2 {\u000A        fmt.Println(\"expected \'foo\' or \'bar\' subcommands\")\u000A        os.Exit(1)\u000A    }\u000A');codeLines.push('    switch os.Args[1] {\u000A');codeLines.push('    case \"foo\":\u000A        fooCmd.Parse(os.Args[2:])\u000A        fmt.Println(\"subcommand \'foo\'\")\u000A        fmt.Println(\"  enable:\", *fooEnable)\u000A        fmt.Println(\"  name:\", *fooName)\u000A        fmt.Println(\"  tail:\", fooCmd.Args())\u000A    case \"bar\":\u000A        barCmd.Parse(os.Args[2:])\u000A        fmt.Println(\"subcommand \'bar\'\")\u000A        fmt.Println(\"  level:\", *barLevel)\u000A        fmt.Println(\"  tail:\", barCmd.Args())\u000A    default:\u000A        fmt.Println(\"expected \'foo\' or \'bar\' subcommands\")\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"flag\"\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fooCmd :\x3D flag.NewFlagSet(\"foo\", flag.ExitOnError)\u000A    fooEnable :\x3D fooCmd.Bool(\"enable\", false, \"enable\")\u000A    fooName :\x3D fooCmd.String(\"name\", \"\", \"name\")\u000A');codeLines.push('    barCmd :\x3D flag.NewFlagSet(\"bar\", flag.ExitOnError)\u000A    barLevel :\x3D barCmd.Int(\"level\", 0, \"level\")\u000A');codeLines.push('    if len(os.Args) \x3C 2 {\u000A        fmt.Println(\"expected \'foo\' or \'bar\' subcommands\")\u000A        os.Exit(1)\u000A    }\u000A');codeLines.push('    switch os.Args[1] {\u000A');codeLines.push('    case \"foo\":\u000A        fooCmd.Parse(os.Args[2:])\u000A        fmt.Println(\"subcommand \'foo\'\")\u000A        fmt.Println(\"  enable:\", *fooEnable)\u000A        fmt.Println(\"  name:\", *fooName)\u000A        fmt.Println(\"  tail:\", fooCmd.Args())\u000A    case \"bar\":\u000A        barCmd.Parse(os.Args[2:])\u000A        fmt.Println(\"subcommand \'bar\'\")\u000A        fmt.Println(\"  level:\", *barLevel)\u000A        fmt.Println(\"  tail:\", barCmd.Args())\u000A    default:\u000A        fmt.Println(\"expected \'foo\' or \'bar\' subcommands\")\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/constants b/public/constants
index b1cf880..737bfc0 100644
--- a/public/constants
+++ b/public/constants
@@ -183,7 +183,7 @@ assignment or function call. For example, here
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math\"\u000A)\u000A');codeLines.push('const s string = \"constant\"\u000A');codeLines.push('func main() {\u000A    fmt.Println(s)\u000A');codeLines.push('    const n = 500000000\u000A');codeLines.push('    const d = 3e20 / n\u000A    fmt.Println(d)\u000A');codeLines.push('    fmt.Println(int64(d))\u000A');codeLines.push('    fmt.Println(math.Sin(n))\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math\"\u000A)\u000A');codeLines.push('const s string \x3D \"constant\"\u000A');codeLines.push('func main() {\u000A    fmt.Println(s)\u000A');codeLines.push('    const n \x3D 500000000\u000A');codeLines.push('    const d \x3D 3e20 / n\u000A    fmt.Println(d)\u000A');codeLines.push('    fmt.Println(int64(d))\u000A');codeLines.push('    fmt.Println(math.Sin(n))\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/context b/public/context
index 3a3a406..d808591 100644
--- a/public/context
+++ b/public/context
@@ -205,7 +205,7 @@ cancellation.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net/http\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func hello(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    ctx := req.Context()\u000A    fmt.Println(\"server: hello handler started\")\u000A    defer fmt.Println(\"server: hello handler ended\")\u000A');codeLines.push('    select {\u000A    case \x3C-time.After(10 * time.Second):\u000A        fmt.Fprintf(w, \"hello\\n\")\u000A    case \x3C-ctx.Done():\u000A');codeLines.push('        err := ctx.Err()\u000A        fmt.Println(\"server:\", err)\u000A        internalError := http.StatusInternalServerError\u000A        http.Error(w, err.Error(), internalError)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    http.HandleFunc(\"/hello\", hello)\u000A    http.ListenAndServe(\":8090\", nil)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net/http\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func hello(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    ctx :\x3D req.Context()\u000A    fmt.Println(\"server: hello handler started\")\u000A    defer fmt.Println(\"server: hello handler ended\")\u000A');codeLines.push('    select {\u000A    case \x3C-time.After(10 * time.Second):\u000A        fmt.Fprintf(w, \"hello\\n\")\u000A    case \x3C-ctx.Done():\u000A');codeLines.push('        err :\x3D ctx.Err()\u000A        fmt.Println(\"server:\", err)\u000A        internalError :\x3D http.StatusInternalServerError\u000A        http.Error(w, err.Error(), internalError)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    http.HandleFunc(\"/hello\", hello)\u000A    http.ListenAndServe(\":8090\", nil)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/defer b/public/defer
index 54bb2d7..b15ef1e 100644
--- a/public/defer
+++ b/public/defer
@@ -212,7 +212,7 @@ after being written.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f := createFile(\"/tmp/defer.txt\")\u000A    defer closeFile(f)\u000A    writeFile(f)\u000A}\u000A');codeLines.push('func createFile(p string) *os.File {\u000A    fmt.Println(\"creating\")\u000A    f, err := os.Create(p)\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    return f\u000A}\u000A');codeLines.push('func writeFile(f *os.File) {\u000A    fmt.Println(\"writing\")\u000A    fmt.Fprintln(f, \"data\")\u000A');codeLines.push('}\u000A');codeLines.push('func closeFile(f *os.File) {\u000A    fmt.Println(\"closing\")\u000A    err := f.Close()\u000A');codeLines.push('    if err != nil {\u000A        fmt.Fprintf(os.Stderr, \"error: %v\\n\", err)\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f :\x3D createFile(\"/tmp/defer.txt\")\u000A    defer closeFile(f)\u000A    writeFile(f)\u000A}\u000A');codeLines.push('func createFile(p string) *os.File {\u000A    fmt.Println(\"creating\")\u000A    f, err :\x3D os.Create(p)\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    return f\u000A}\u000A');codeLines.push('func writeFile(f *os.File) {\u000A    fmt.Println(\"writing\")\u000A    fmt.Fprintln(f, \"data\")\u000A');codeLines.push('}\u000A');codeLines.push('func closeFile(f *os.File) {\u000A    fmt.Println(\"closing\")\u000A    err :\x3D f.Close()\u000A');codeLines.push('    if err !\x3D nil {\u000A        fmt.Fprintf(os.Stderr, \"error: %v\\n\", err)\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/directories b/public/directories
index c88a76c..0d7d9f5 100644
--- a/public/directories
+++ b/public/directories
@@ -353,7 +353,7 @@ recursively by <code>filepath.Walk</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A    \"path/filepath\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e != nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    err := os.Mkdir(\"subdir\", 0755)\u000A    check(err)\u000A');codeLines.push('    defer os.RemoveAll(\"subdir\")\u000A');codeLines.push('    createEmptyFile := func(name string) {\u000A        d := []byte(\"\")\u000A        check(ioutil.WriteFile(name, d, 0644))\u000A    }\u000A');codeLines.push('    createEmptyFile(\"subdir/file1\")\u000A');codeLines.push('    err = os.MkdirAll(\"subdir/parent/child\", 0755)\u000A    check(err)\u000A');codeLines.push('    createEmptyFile(\"subdir/parent/file2\")\u000A    createEmptyFile(\"subdir/parent/file3\")\u000A    createEmptyFile(\"subdir/parent/child/file4\")\u000A');codeLines.push('    c, err := ioutil.ReadDir(\"subdir/parent\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Listing subdir/parent\")\u000A    for _, entry := range c {\u000A        fmt.Println(\" \", entry.Name(), entry.IsDir())\u000A    }\u000A');codeLines.push('    err = os.Chdir(\"subdir/parent/child\")\u000A    check(err)\u000A');codeLines.push('    c, err = ioutil.ReadDir(\".\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Listing subdir/parent/child\")\u000A    for _, entry := range c {\u000A        fmt.Println(\" \", entry.Name(), entry.IsDir())\u000A    }\u000A');codeLines.push('    err = os.Chdir(\"../../..\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Visiting subdir\")\u000A    err = filepath.Walk(\"subdir\", visit)\u000A}\u000A');codeLines.push('func visit(p string, info os.FileInfo, err error) error {\u000A    if err != nil {\u000A        return err\u000A    }\u000A    fmt.Println(\" \", p, info.IsDir())\u000A    return nil\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A    \"path/filepath\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e !\x3D nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    err :\x3D os.Mkdir(\"subdir\", 0755)\u000A    check(err)\u000A');codeLines.push('    defer os.RemoveAll(\"subdir\")\u000A');codeLines.push('    createEmptyFile :\x3D func(name string) {\u000A        d :\x3D []byte(\"\")\u000A        check(ioutil.WriteFile(name, d, 0644))\u000A    }\u000A');codeLines.push('    createEmptyFile(\"subdir/file1\")\u000A');codeLines.push('    err \x3D os.MkdirAll(\"subdir/parent/child\", 0755)\u000A    check(err)\u000A');codeLines.push('    createEmptyFile(\"subdir/parent/file2\")\u000A    createEmptyFile(\"subdir/parent/file3\")\u000A    createEmptyFile(\"subdir/parent/child/file4\")\u000A');codeLines.push('    c, err :\x3D ioutil.ReadDir(\"subdir/parent\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Listing subdir/parent\")\u000A    for _, entry :\x3D range c {\u000A        fmt.Println(\" \", entry.Name(), entry.IsDir())\u000A    }\u000A');codeLines.push('    err \x3D os.Chdir(\"subdir/parent/child\")\u000A    check(err)\u000A');codeLines.push('    c, err \x3D ioutil.ReadDir(\".\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Listing subdir/parent/child\")\u000A    for _, entry :\x3D range c {\u000A        fmt.Println(\" \", entry.Name(), entry.IsDir())\u000A    }\u000A');codeLines.push('    err \x3D os.Chdir(\"../../..\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Visiting subdir\")\u000A    err \x3D filepath.Walk(\"subdir\", visit)\u000A}\u000A');codeLines.push('func visit(p string, info os.FileInfo, err error) error {\u000A    if err !\x3D nil {\u000A        return err\u000A    }\u000A    fmt.Println(\" \", p, info.IsDir())\u000A    return nil\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/environment-variables b/public/environment-variables
index e68934d..65b18c9 100644
--- a/public/environment-variables
+++ b/public/environment-variables
@@ -186,7 +186,7 @@ program picks that value up.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    os.Setenv(\"FOO\", \"1\")\u000A    fmt.Println(\"FOO:\", os.Getenv(\"FOO\"))\u000A    fmt.Println(\"BAR:\", os.Getenv(\"BAR\"))\u000A');codeLines.push('    fmt.Println()\u000A    for _, e := range os.Environ() {\u000A        pair := strings.SplitN(e, \"=\", 2)\u000A        fmt.Println(pair[0])\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    os.Setenv(\"FOO\", \"1\")\u000A    fmt.Println(\"FOO:\", os.Getenv(\"FOO\"))\u000A    fmt.Println(\"BAR:\", os.Getenv(\"BAR\"))\u000A');codeLines.push('    fmt.Println()\u000A    for _, e :\x3D range os.Environ() {\u000A        pair :\x3D strings.SplitN(e, \"\x3D\", 2)\u000A        fmt.Println(pair[0])\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/epoch b/public/epoch
index 02bfc7e..192c24c 100644
--- a/public/epoch
+++ b/public/epoch
@@ -177,7 +177,7 @@ parsing and formatting.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    now := time.Now()\u000A    secs := now.Unix()\u000A    nanos := now.UnixNano()\u000A    fmt.Println(now)\u000A');codeLines.push('    millis := nanos / 1000000\u000A    fmt.Println(secs)\u000A    fmt.Println(millis)\u000A    fmt.Println(nanos)\u000A');codeLines.push('    fmt.Println(time.Unix(secs, 0))\u000A    fmt.Println(time.Unix(0, nanos))\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    now :\x3D time.Now()\u000A    secs :\x3D now.Unix()\u000A    nanos :\x3D now.UnixNano()\u000A    fmt.Println(now)\u000A');codeLines.push('    millis :\x3D nanos / 1000000\u000A    fmt.Println(secs)\u000A    fmt.Println(millis)\u000A    fmt.Println(nanos)\u000A');codeLines.push('    fmt.Println(time.Unix(secs, 0))\u000A    fmt.Println(time.Unix(0, nanos))\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/errors b/public/errors
index 3103a2e..be57978 100644
--- a/public/errors
+++ b/public/errors
@@ -299,7 +299,7 @@ on the Go blog for more on error handling.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"errors\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func f1(arg int) (int, error) {\u000A    if arg == 42 {\u000A');codeLines.push('        return -1, errors.New(\"can\'t work with 42\")\u000A');codeLines.push('    }\u000A');codeLines.push('    return arg + 3, nil\u000A}\u000A');codeLines.push('type argError struct {\u000A    arg  int\u000A    prob string\u000A}\u000A');codeLines.push('func (e *argError) Error() string {\u000A    return fmt.Sprintf(\"%d - %s\", e.arg, e.prob)\u000A}\u000A');codeLines.push('func f2(arg int) (int, error) {\u000A    if arg == 42 {\u000A');codeLines.push('        return -1, &argError{arg, \"can\'t work with it\"}\u000A    }\u000A    return arg + 3, nil\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    for _, i := range []int{7, 42} {\u000A        if r, e := f1(i); e != nil {\u000A            fmt.Println(\"f1 failed:\", e)\u000A        } else {\u000A            fmt.Println(\"f1 worked:\", r)\u000A        }\u000A    }\u000A    for _, i := range []int{7, 42} {\u000A        if r, e := f2(i); e != nil {\u000A            fmt.Println(\"f2 failed:\", e)\u000A        } else {\u000A            fmt.Println(\"f2 worked:\", r)\u000A        }\u000A    }\u000A');codeLines.push('    _, e := f2(42)\u000A    if ae, ok := e.(*argError); ok {\u000A        fmt.Println(ae.arg)\u000A        fmt.Println(ae.prob)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"errors\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func f1(arg int) (int, error) {\u000A    if arg \x3D\x3D 42 {\u000A');codeLines.push('        return -1, errors.New(\"can\'t work with 42\")\u000A');codeLines.push('    }\u000A');codeLines.push('    return arg + 3, nil\u000A}\u000A');codeLines.push('type argError struct {\u000A    arg  int\u000A    prob string\u000A}\u000A');codeLines.push('func (e *argError) Error() string {\u000A    return fmt.Sprintf(\"%d - %s\", e.arg, e.prob)\u000A}\u000A');codeLines.push('func f2(arg int) (int, error) {\u000A    if arg \x3D\x3D 42 {\u000A');codeLines.push('        return -1, \x26argError{arg, \"can\'t work with it\"}\u000A    }\u000A    return arg + 3, nil\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    for _, i :\x3D range []int{7, 42} {\u000A        if r, e :\x3D f1(i); e !\x3D nil {\u000A            fmt.Println(\"f1 failed:\", e)\u000A        } else {\u000A            fmt.Println(\"f1 worked:\", r)\u000A        }\u000A    }\u000A    for _, i :\x3D range []int{7, 42} {\u000A        if r, e :\x3D f2(i); e !\x3D nil {\u000A            fmt.Println(\"f2 failed:\", e)\u000A        } else {\u000A            fmt.Println(\"f2 worked:\", r)\u000A        }\u000A    }\u000A');codeLines.push('    _, e :\x3D f2(42)\u000A    if ae, ok :\x3D e.(*argError); ok {\u000A        fmt.Println(ae.arg)\u000A        fmt.Println(ae.prob)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/execing-processes b/public/execing-processes
index 585a266..687da4a 100644
--- a/public/execing-processes
+++ b/public/execing-processes
@@ -203,7 +203,7 @@ processes covers most use cases for <code>fork</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"os\"\u000A    \"os/exec\"\u000A    \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    binary, lookErr := exec.LookPath(\"ls\")\u000A    if lookErr != nil {\u000A        panic(lookErr)\u000A    }\u000A');codeLines.push('    args := []string{\"ls\", \"-a\", \"-l\", \"-h\"}\u000A');codeLines.push('    env := os.Environ()\u000A');codeLines.push('    execErr := syscall.Exec(binary, args, env)\u000A    if execErr != nil {\u000A        panic(execErr)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"os\"\u000A    \"os/exec\"\u000A    \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    binary, lookErr :\x3D exec.LookPath(\"ls\")\u000A    if lookErr !\x3D nil {\u000A        panic(lookErr)\u000A    }\u000A');codeLines.push('    args :\x3D []string{\"ls\", \"-a\", \"-l\", \"-h\"}\u000A');codeLines.push('    env :\x3D os.Environ()\u000A');codeLines.push('    execErr :\x3D syscall.Exec(binary, args, env)\u000A    if execErr !\x3D nil {\u000A        panic(execErr)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/file-paths b/public/file-paths
index 3219a93..1e5e204 100644
--- a/public/file-paths
+++ b/public/file-paths
@@ -250,7 +250,7 @@ be made relative to base.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"path/filepath\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p := filepath.Join(\"dir1\", \"dir2\", \"filename\")\u000A    fmt.Println(\"p:\", p)\u000A');codeLines.push('    fmt.Println(filepath.Join(\"dir1//\", \"filename\"))\u000A    fmt.Println(filepath.Join(\"dir1/../dir1\", \"filename\"))\u000A');codeLines.push('    fmt.Println(\"Dir(p):\", filepath.Dir(p))\u000A    fmt.Println(\"Base(p):\", filepath.Base(p))\u000A');codeLines.push('    fmt.Println(filepath.IsAbs(\"dir/file\"))\u000A    fmt.Println(filepath.IsAbs(\"/dir/file\"))\u000A');codeLines.push('    filename := \"config.json\"\u000A');codeLines.push('    ext := filepath.Ext(filename)\u000A    fmt.Println(ext)\u000A');codeLines.push('    fmt.Println(strings.TrimSuffix(filename, ext))\u000A');codeLines.push('    rel, err := filepath.Rel(\"a/b\", \"a/b/t/file\")\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(rel)\u000A');codeLines.push('    rel, err = filepath.Rel(\"a/b\", \"a/c/t/file\")\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(rel)\u000A}\u000A');codeLines.push('');
+      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"path/filepath\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p :\x3D filepath.Join(\"dir1\", \"dir2\", \"filename\")\u000A    fmt.Println(\"p:\", p)\u000A');codeLines.push('    fmt.Println(filepath.Join(\"dir1//\", \"filename\"))\u000A    fmt.Println(filepath.Join(\"dir1/../dir1\", \"filename\"))\u000A');codeLines.push('    fmt.Println(\"Dir(p):\", filepath.Dir(p))\u000A    fmt.Println(\"Base(p):\", filepath.Base(p))\u000A');codeLines.push('    fmt.Println(filepath.IsAbs(\"dir/file\"))\u000A    fmt.Println(filepath.IsAbs(\"/dir/file\"))\u000A');codeLines.push('    filename :\x3D \"config.json\"\u000A');codeLines.push('    ext :\x3D filepath.Ext(filename)\u000A    fmt.Println(ext)\u000A');codeLines.push('    fmt.Println(strings.TrimSuffix(filename, ext))\u000A');codeLines.push('    rel, err :\x3D filepath.Rel(\"a/b\", \"a/b/t/file\")\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(rel)\u000A');codeLines.push('    rel, err \x3D filepath.Rel(\"a/b\", \"a/c/t/file\")\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(rel)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/for b/public/for
index fea862c..d4abec4 100644
--- a/public/for
+++ b/public/for
@@ -195,7 +195,7 @@ structures.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    i := 1\u000A    for i \x3C= 3 {\u000A        fmt.Println(i)\u000A        i = i + 1\u000A    }\u000A');codeLines.push('    for j := 7; j \x3C= 9; j++ {\u000A        fmt.Println(j)\u000A    }\u000A');codeLines.push('    for {\u000A        fmt.Println(\"loop\")\u000A        break\u000A    }\u000A');codeLines.push('    for n := 0; n \x3C= 5; n++ {\u000A        if n%2 == 0 {\u000A            continue\u000A        }\u000A        fmt.Println(n)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    i :\x3D 1\u000A    for i \x3C\x3D 3 {\u000A        fmt.Println(i)\u000A        i \x3D i + 1\u000A    }\u000A');codeLines.push('    for j :\x3D 7; j \x3C\x3D 9; j++ {\u000A        fmt.Println(j)\u000A    }\u000A');codeLines.push('    for {\u000A        fmt.Println(\"loop\")\u000A        break\u000A    }\u000A');codeLines.push('    for n :\x3D 0; n \x3C\x3D 5; n++ {\u000A        if n%2 \x3D\x3D 0 {\u000A            continue\u000A        }\u000A        fmt.Println(n)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/functions b/public/functions
index b4b80b3..2747daa 100644
--- a/public/functions
+++ b/public/functions
@@ -193,7 +193,7 @@ multiple return values, which we&rsquo;ll look at next.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func plus(a int, b int) int {\u000A');codeLines.push('    return a + b\u000A}\u000A');codeLines.push('func plusPlus(a, b, c int) int {\u000A    return a + b + c\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    res := plus(1, 2)\u000A    fmt.Println(\"1+2 =\", res)\u000A');codeLines.push('    res = plusPlus(1, 2, 3)\u000A    fmt.Println(\"1+2+3 =\", res)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func plus(a int, b int) int {\u000A');codeLines.push('    return a + b\u000A}\u000A');codeLines.push('func plusPlus(a, b, c int) int {\u000A    return a + b + c\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    res :\x3D plus(1, 2)\u000A    fmt.Println(\"1+2 \x3D\", res)\u000A');codeLines.push('    res \x3D plusPlus(1, 2, 3)\u000A    fmt.Println(\"1+2+3 \x3D\", res)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/goroutines b/public/goroutines
index 105d9bd..0defc4c 100644
--- a/public/goroutines
+++ b/public/goroutines
@@ -207,7 +207,7 @@ concurrent Go programs: channels.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func f(from string) {\u000A    for i := 0; i \x3C 3; i++ {\u000A        fmt.Println(from, \":\", i)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f(\"direct\")\u000A');codeLines.push('    go f(\"goroutine\")\u000A');codeLines.push('    go func(msg string) {\u000A        fmt.Println(msg)\u000A    }(\"going\")\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func f(from string) {\u000A    for i :\x3D 0; i \x3C 3; i++ {\u000A        fmt.Println(from, \":\", i)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f(\"direct\")\u000A');codeLines.push('    go f(\"goroutine\")\u000A');codeLines.push('    go func(msg string) {\u000A        fmt.Println(msg)\u000A    }(\"going\")\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/http-clients b/public/http-clients
index 09080b5..d3c773d 100644
--- a/public/http-clients
+++ b/public/http-clients
@@ -169,7 +169,7 @@ settings.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"net/http\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    resp, err := http.Get(\"http://gobyexample.com\")\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    defer resp.Body.Close()\u000A');codeLines.push('    fmt.Println(\"Response status:\", resp.Status)\u000A');codeLines.push('    scanner := bufio.NewScanner(resp.Body)\u000A    for i := 0; scanner.Scan() && i \x3C 5; i++ {\u000A        fmt.Println(scanner.Text())\u000A    }\u000A');codeLines.push('    if err := scanner.Err(); err != nil {\u000A        panic(err)\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"net/http\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    resp, err :\x3D http.Get(\"http://gobyexample.com\")\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    defer resp.Body.Close()\u000A');codeLines.push('    fmt.Println(\"Response status:\", resp.Status)\u000A');codeLines.push('    scanner :\x3D bufio.NewScanner(resp.Body)\u000A    for i :\x3D 0; scanner.Scan() \x26\x26 i \x3C 5; i++ {\u000A        fmt.Println(scanner.Text())\u000A    }\u000A');codeLines.push('    if err :\x3D scanner.Err(); err !\x3D nil {\u000A        panic(err)\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/http-servers b/public/http-servers
index c62ba61..72b4ef0 100644
--- a/public/http-servers
+++ b/public/http-servers
@@ -210,7 +210,7 @@ router we&rsquo;ve just set up.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net/http\"\u000A)\u000A');codeLines.push('func hello(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    fmt.Fprintf(w, \"hello\\n\")\u000A}\u000A');codeLines.push('func headers(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    for name, headers := range req.Header {\u000A        for _, h := range headers {\u000A            fmt.Fprintf(w, \"%v: %v\\n\", name, h)\u000A        }\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    http.HandleFunc(\"/hello\", hello)\u000A    http.HandleFunc(\"/headers\", headers)\u000A');codeLines.push('    http.ListenAndServe(\":8090\", nil)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net/http\"\u000A)\u000A');codeLines.push('func hello(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    fmt.Fprintf(w, \"hello\\n\")\u000A}\u000A');codeLines.push('func headers(w http.ResponseWriter, req *http.Request) {\u000A');codeLines.push('    for name, headers :\x3D range req.Header {\u000A        for _, h :\x3D range headers {\u000A            fmt.Fprintf(w, \"%v: %v\\n\", name, h)\u000A        }\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    http.HandleFunc(\"/hello\", hello)\u000A    http.HandleFunc(\"/headers\", headers)\u000A');codeLines.push('    http.ListenAndServe(\":8090\", nil)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/if-else b/public/if-else
index ed87d6a..b599e09 100644
--- a/public/if-else
+++ b/public/if-else
@@ -184,7 +184,7 @@ for basic conditions.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    if 7%2 == 0 {\u000A        fmt.Println(\"7 is even\")\u000A    } else {\u000A        fmt.Println(\"7 is odd\")\u000A    }\u000A');codeLines.push('    if 8%4 == 0 {\u000A        fmt.Println(\"8 is divisible by 4\")\u000A    }\u000A');codeLines.push('    if num := 9; num \x3C 0 {\u000A        fmt.Println(num, \"is negative\")\u000A    } else if num \x3C 10 {\u000A        fmt.Println(num, \"has 1 digit\")\u000A    } else {\u000A        fmt.Println(num, \"has multiple digits\")\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    if 7%2 \x3D\x3D 0 {\u000A        fmt.Println(\"7 is even\")\u000A    } else {\u000A        fmt.Println(\"7 is odd\")\u000A    }\u000A');codeLines.push('    if 8%4 \x3D\x3D 0 {\u000A        fmt.Println(\"8 is divisible by 4\")\u000A    }\u000A');codeLines.push('    if num :\x3D 9; num \x3C 0 {\u000A        fmt.Println(num, \"is negative\")\u000A    } else if num \x3C 10 {\u000A        fmt.Println(num, \"has 1 digit\")\u000A    } else {\u000A        fmt.Println(num, \"has multiple digits\")\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/interfaces b/public/interfaces
index 737c518..baf76af 100644
--- a/public/interfaces
+++ b/public/interfaces
@@ -236,7 +236,7 @@ these structs as arguments to <code>measure</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math\"\u000A)\u000A');codeLines.push('type geometry interface {\u000A    area() float64\u000A    perim() float64\u000A}\u000A');codeLines.push('type rect struct {\u000A    width, height float64\u000A}\u000Atype circle struct {\u000A    radius float64\u000A}\u000A');codeLines.push('func (r rect) area() float64 {\u000A    return r.width * r.height\u000A}\u000Afunc (r rect) perim() float64 {\u000A    return 2*r.width + 2*r.height\u000A}\u000A');codeLines.push('func (c circle) area() float64 {\u000A    return math.Pi * c.radius * c.radius\u000A}\u000Afunc (c circle) perim() float64 {\u000A    return 2 * math.Pi * c.radius\u000A}\u000A');codeLines.push('func measure(g geometry) {\u000A    fmt.Println(g)\u000A    fmt.Println(g.area())\u000A    fmt.Println(g.perim())\u000A}\u000A');codeLines.push('func main() {\u000A    r := rect{width: 3, height: 4}\u000A    c := circle{radius: 5}\u000A');codeLines.push('    measure(r)\u000A    measure(c)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math\"\u000A)\u000A');codeLines.push('type geometry interface {\u000A    area() float64\u000A    perim() float64\u000A}\u000A');codeLines.push('type rect struct {\u000A    width, height float64\u000A}\u000Atype circle struct {\u000A    radius float64\u000A}\u000A');codeLines.push('func (r rect) area() float64 {\u000A    return r.width * r.height\u000A}\u000Afunc (r rect) perim() float64 {\u000A    return 2*r.width + 2*r.height\u000A}\u000A');codeLines.push('func (c circle) area() float64 {\u000A    return math.Pi * c.radius * c.radius\u000A}\u000Afunc (c circle) perim() float64 {\u000A    return 2 * math.Pi * c.radius\u000A}\u000A');codeLines.push('func measure(g geometry) {\u000A    fmt.Println(g)\u000A    fmt.Println(g.area())\u000A    fmt.Println(g.perim())\u000A}\u000A');codeLines.push('func main() {\u000A    r :\x3D rect{width: 3, height: 4}\u000A    c :\x3D circle{radius: 5}\u000A');codeLines.push('    measure(r)\u000A    measure(c)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/json b/public/json
index 4a648d1..b39d512 100644
--- a/public/json
+++ b/public/json
@@ -416,7 +416,7 @@ for more.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"encoding/json\"\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('type response1 struct {\u000A    Page   int\u000A    Fruits []string\u000A}\u000A');codeLines.push('type response2 struct {\u000A    Page   int      `json:\"page\"`\u000A    Fruits []string `json:\"fruits\"`\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    bolB, _ := json.Marshal(true)\u000A    fmt.Println(string(bolB))\u000A');codeLines.push('    intB, _ := json.Marshal(1)\u000A    fmt.Println(string(intB))\u000A');codeLines.push('    fltB, _ := json.Marshal(2.34)\u000A    fmt.Println(string(fltB))\u000A');codeLines.push('    strB, _ := json.Marshal(\"gopher\")\u000A    fmt.Println(string(strB))\u000A');codeLines.push('    slcD := []string{\"apple\", \"peach\", \"pear\"}\u000A    slcB, _ := json.Marshal(slcD)\u000A    fmt.Println(string(slcB))\u000A');codeLines.push('    mapD := map[string]int{\"apple\": 5, \"lettuce\": 7}\u000A    mapB, _ := json.Marshal(mapD)\u000A    fmt.Println(string(mapB))\u000A');codeLines.push('    res1D := &response1{\u000A        Page:   1,\u000A        Fruits: []string{\"apple\", \"peach\", \"pear\"}}\u000A    res1B, _ := json.Marshal(res1D)\u000A    fmt.Println(string(res1B))\u000A');codeLines.push('    res2D := &response2{\u000A        Page:   1,\u000A        Fruits: []string{\"apple\", \"peach\", \"pear\"}}\u000A    res2B, _ := json.Marshal(res2D)\u000A    fmt.Println(string(res2B))\u000A');codeLines.push('    byt := []byte(`{\"num\":6.13,\"strs\":[\"a\",\"b\"]}`)\u000A');codeLines.push('    var dat map[string]interface{}\u000A');codeLines.push('    if err := json.Unmarshal(byt, &dat); err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(dat)\u000A');codeLines.push('    num := dat[\"num\"].(float64)\u000A    fmt.Println(num)\u000A');codeLines.push('    strs := dat[\"strs\"].([]interface{})\u000A    str1 := strs[0].(string)\u000A    fmt.Println(str1)\u000A');codeLines.push('    str := `{\"page\": 1, \"fruits\": [\"apple\", \"peach\"]}`\u000A    res := response2{}\u000A    json.Unmarshal([]byte(str), &res)\u000A    fmt.Println(res)\u000A    fmt.Println(res.Fruits[0])\u000A');codeLines.push('    enc := json.NewEncoder(os.Stdout)\u000A    d := map[string]int{\"apple\": 5, \"lettuce\": 7}\u000A    enc.Encode(d)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"encoding/json\"\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('type response1 struct {\u000A    Page   int\u000A    Fruits []string\u000A}\u000A');codeLines.push('type response2 struct {\u000A    Page   int      `json:\"page\"`\u000A    Fruits []string `json:\"fruits\"`\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    bolB, _ :\x3D json.Marshal(true)\u000A    fmt.Println(string(bolB))\u000A');codeLines.push('    intB, _ :\x3D json.Marshal(1)\u000A    fmt.Println(string(intB))\u000A');codeLines.push('    fltB, _ :\x3D json.Marshal(2.34)\u000A    fmt.Println(string(fltB))\u000A');codeLines.push('    strB, _ :\x3D json.Marshal(\"gopher\")\u000A    fmt.Println(string(strB))\u000A');codeLines.push('    slcD :\x3D []string{\"apple\", \"peach\", \"pear\"}\u000A    slcB, _ :\x3D json.Marshal(slcD)\u000A    fmt.Println(string(slcB))\u000A');codeLines.push('    mapD :\x3D map[string]int{\"apple\": 5, \"lettuce\": 7}\u000A    mapB, _ :\x3D json.Marshal(mapD)\u000A    fmt.Println(string(mapB))\u000A');codeLines.push('    res1D :\x3D \x26response1{\u000A        Page:   1,\u000A        Fruits: []string{\"apple\", \"peach\", \"pear\"}}\u000A    res1B, _ :\x3D json.Marshal(res1D)\u000A    fmt.Println(string(res1B))\u000A');codeLines.push('    res2D :\x3D \x26response2{\u000A        Page:   1,\u000A        Fruits: []string{\"apple\", \"peach\", \"pear\"}}\u000A    res2B, _ :\x3D json.Marshal(res2D)\u000A    fmt.Println(string(res2B))\u000A');codeLines.push('    byt :\x3D []byte(`{\"num\":6.13,\"strs\":[\"a\",\"b\"]}`)\u000A');codeLines.push('    var dat map[string]interface{}\u000A');codeLines.push('    if err :\x3D json.Unmarshal(byt, \x26dat); err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(dat)\u000A');codeLines.push('    num :\x3D dat[\"num\"].(float64)\u000A    fmt.Println(num)\u000A');codeLines.push('    strs :\x3D dat[\"strs\"].([]interface{})\u000A    str1 :\x3D strs[0].(string)\u000A    fmt.Println(str1)\u000A');codeLines.push('    str :\x3D `{\"page\": 1, \"fruits\": [\"apple\", \"peach\"]}`\u000A    res :\x3D response2{}\u000A    json.Unmarshal([]byte(str), \x26res)\u000A    fmt.Println(res)\u000A    fmt.Println(res.Fruits[0])\u000A');codeLines.push('    enc :\x3D json.NewEncoder(os.Stdout)\u000A    d :\x3D map[string]int{\"apple\": 5, \"lettuce\": 7}\u000A    enc.Encode(d)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/line-filters b/public/line-filters
index ec84915..d7e5fea 100644
--- a/public/line-filters
+++ b/public/line-filters
@@ -204,7 +204,7 @@ lowercase lines.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"os\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    scanner := bufio.NewScanner(os.Stdin)\u000A');codeLines.push('    for scanner.Scan() {\u000A');codeLines.push('        ucl := strings.ToUpper(scanner.Text())\u000A');codeLines.push('        fmt.Println(ucl)\u000A    }\u000A');codeLines.push('    if err := scanner.Err(); err != nil {\u000A        fmt.Fprintln(os.Stderr, \"error:\", err)\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"os\"\u000A    \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    scanner :\x3D bufio.NewScanner(os.Stdin)\u000A');codeLines.push('    for scanner.Scan() {\u000A');codeLines.push('        ucl :\x3D strings.ToUpper(scanner.Text())\u000A');codeLines.push('        fmt.Println(ucl)\u000A    }\u000A');codeLines.push('    if err :\x3D scanner.Err(); err !\x3D nil {\u000A        fmt.Fprintln(os.Stderr, \"error:\", err)\u000A        os.Exit(1)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/maps b/public/maps
index f0c7c0f..c3bb882 100644
--- a/public/maps
+++ b/public/maps
@@ -232,7 +232,7 @@ printed with <code>fmt.Println</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    m := make(map[string]int)\u000A');codeLines.push('    m[\"k1\"] = 7\u000A    m[\"k2\"] = 13\u000A');codeLines.push('    fmt.Println(\"map:\", m)\u000A');codeLines.push('    v1 := m[\"k1\"]\u000A    fmt.Println(\"v1: \", v1)\u000A');codeLines.push('    fmt.Println(\"len:\", len(m))\u000A');codeLines.push('    delete(m, \"k2\")\u000A    fmt.Println(\"map:\", m)\u000A');codeLines.push('    _, prs := m[\"k2\"]\u000A    fmt.Println(\"prs:\", prs)\u000A');codeLines.push('    n := map[string]int{\"foo\": 1, \"bar\": 2}\u000A    fmt.Println(\"map:\", n)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    m :\x3D make(map[string]int)\u000A');codeLines.push('    m[\"k1\"] \x3D 7\u000A    m[\"k2\"] \x3D 13\u000A');codeLines.push('    fmt.Println(\"map:\", m)\u000A');codeLines.push('    v1 :\x3D m[\"k1\"]\u000A    fmt.Println(\"v1: \", v1)\u000A');codeLines.push('    fmt.Println(\"len:\", len(m))\u000A');codeLines.push('    delete(m, \"k2\")\u000A    fmt.Println(\"map:\", m)\u000A');codeLines.push('    _, prs :\x3D m[\"k2\"]\u000A    fmt.Println(\"prs:\", prs)\u000A');codeLines.push('    n :\x3D map[string]int{\"foo\": 1, \"bar\": 2}\u000A    fmt.Println(\"map:\", n)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/methods b/public/methods
index a053c85..b8e0a58 100644
--- a/public/methods
+++ b/public/methods
@@ -197,7 +197,7 @@ naming related sets of methods: interfaces.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('type rect struct {\u000A    width, height int\u000A}\u000A');codeLines.push('func (r *rect) area() int {\u000A    return r.width * r.height\u000A}\u000A');codeLines.push('func (r rect) perim() int {\u000A    return 2*r.width + 2*r.height\u000A}\u000A');codeLines.push('func main() {\u000A    r := rect{width: 10, height: 5}\u000A');codeLines.push('    fmt.Println(\"area: \", r.area())\u000A    fmt.Println(\"perim:\", r.perim())\u000A');codeLines.push('    rp := &r\u000A    fmt.Println(\"area: \", rp.area())\u000A    fmt.Println(\"perim:\", rp.perim())\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('type rect struct {\u000A    width, height int\u000A}\u000A');codeLines.push('func (r *rect) area() int {\u000A    return r.width * r.height\u000A}\u000A');codeLines.push('func (r rect) perim() int {\u000A    return 2*r.width + 2*r.height\u000A}\u000A');codeLines.push('func main() {\u000A    r :\x3D rect{width: 10, height: 5}\u000A');codeLines.push('    fmt.Println(\"area: \", r.area())\u000A    fmt.Println(\"perim:\", r.perim())\u000A');codeLines.push('    rp :\x3D \x26r\u000A    fmt.Println(\"area: \", rp.area())\u000A    fmt.Println(\"perim:\", rp.perim())\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/multiple-return-values b/public/multiple-return-values
index ec3ebcb..fa3ca35 100644
--- a/public/multiple-return-values
+++ b/public/multiple-return-values
@@ -166,7 +166,7 @@ feature of Go functions; we&rsquo;ll look at this next.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func vals() (int, int) {\u000A    return 3, 7\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    a, b := vals()\u000A    fmt.Println(a)\u000A    fmt.Println(b)\u000A');codeLines.push('    _, c := vals()\u000A    fmt.Println(c)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func vals() (int, int) {\u000A    return 3, 7\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    a, b :\x3D vals()\u000A    fmt.Println(a)\u000A    fmt.Println(b)\u000A');codeLines.push('    _, c :\x3D vals()\u000A    fmt.Println(c)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/mutexes b/public/mutexes
index fb406ee..94208eb 100644
--- a/public/mutexes
+++ b/public/mutexes
@@ -297,7 +297,7 @@ management task using only goroutines and channels.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"sync\"\u000A    \"sync/atomic\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var state = make(map[int]int)\u000A');codeLines.push('    var mutex = &sync.Mutex{}\u000A');codeLines.push('    var readOps uint64\u000A    var writeOps uint64\u000A');codeLines.push('    for r := 0; r \x3C 100; r++ {\u000A        go func() {\u000A            total := 0\u000A            for {\u000A');codeLines.push('                key := rand.Intn(5)\u000A                mutex.Lock()\u000A                total += state[key]\u000A                mutex.Unlock()\u000A                atomic.AddUint64(&readOps, 1)\u000A');codeLines.push('                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    for w := 0; w \x3C 10; w++ {\u000A        go func() {\u000A            for {\u000A                key := rand.Intn(5)\u000A                val := rand.Intn(100)\u000A                mutex.Lock()\u000A                state[key] = val\u000A                mutex.Unlock()\u000A                atomic.AddUint64(&writeOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    time.Sleep(time.Second)\u000A');codeLines.push('    readOpsFinal := atomic.LoadUint64(&readOps)\u000A    fmt.Println(\"readOps:\", readOpsFinal)\u000A    writeOpsFinal := atomic.LoadUint64(&writeOps)\u000A    fmt.Println(\"writeOps:\", writeOpsFinal)\u000A');codeLines.push('    mutex.Lock()\u000A    fmt.Println(\"state:\", state)\u000A    mutex.Unlock()\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"sync\"\u000A    \"sync/atomic\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var state \x3D make(map[int]int)\u000A');codeLines.push('    var mutex \x3D \x26sync.Mutex{}\u000A');codeLines.push('    var readOps uint64\u000A    var writeOps uint64\u000A');codeLines.push('    for r :\x3D 0; r \x3C 100; r++ {\u000A        go func() {\u000A            total :\x3D 0\u000A            for {\u000A');codeLines.push('                key :\x3D rand.Intn(5)\u000A                mutex.Lock()\u000A                total +\x3D state[key]\u000A                mutex.Unlock()\u000A                atomic.AddUint64(\x26readOps, 1)\u000A');codeLines.push('                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    for w :\x3D 0; w \x3C 10; w++ {\u000A        go func() {\u000A            for {\u000A                key :\x3D rand.Intn(5)\u000A                val :\x3D rand.Intn(100)\u000A                mutex.Lock()\u000A                state[key] \x3D val\u000A                mutex.Unlock()\u000A                atomic.AddUint64(\x26writeOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    time.Sleep(time.Second)\u000A');codeLines.push('    readOpsFinal :\x3D atomic.LoadUint64(\x26readOps)\u000A    fmt.Println(\"readOps:\", readOpsFinal)\u000A    writeOpsFinal :\x3D atomic.LoadUint64(\x26writeOps)\u000A    fmt.Println(\"writeOps:\", writeOpsFinal)\u000A');codeLines.push('    mutex.Lock()\u000A    fmt.Println(\"state:\", state)\u000A    mutex.Unlock()\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/non-blocking-channel-operations b/public/non-blocking-channel-operations
index 6a529c8..ea30fd1 100644
--- a/public/non-blocking-channel-operations
+++ b/public/non-blocking-channel-operations
@@ -176,7 +176,7 @@ on both <code>messages</code> and <code>signals</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A    messages := make(chan string)\u000A    signals := make(chan bool)\u000A');codeLines.push('    select {\u000A    case msg := \x3C-messages:\u000A        fmt.Println(\"received message\", msg)\u000A    default:\u000A        fmt.Println(\"no message received\")\u000A    }\u000A');codeLines.push('    msg := \"hi\"\u000A    select {\u000A    case messages \x3C- msg:\u000A        fmt.Println(\"sent message\", msg)\u000A    default:\u000A        fmt.Println(\"no message sent\")\u000A    }\u000A');codeLines.push('    select {\u000A    case msg := \x3C-messages:\u000A        fmt.Println(\"received message\", msg)\u000A    case sig := \x3C-signals:\u000A        fmt.Println(\"received signal\", sig)\u000A    default:\u000A        fmt.Println(\"no activity\")\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A    messages :\x3D make(chan string)\u000A    signals :\x3D make(chan bool)\u000A');codeLines.push('    select {\u000A    case msg :\x3D \x3C-messages:\u000A        fmt.Println(\"received message\", msg)\u000A    default:\u000A        fmt.Println(\"no message received\")\u000A    }\u000A');codeLines.push('    msg :\x3D \"hi\"\u000A    select {\u000A    case messages \x3C- msg:\u000A        fmt.Println(\"sent message\", msg)\u000A    default:\u000A        fmt.Println(\"no message sent\")\u000A    }\u000A');codeLines.push('    select {\u000A    case msg :\x3D \x3C-messages:\u000A        fmt.Println(\"received message\", msg)\u000A    case sig :\x3D \x3C-signals:\u000A        fmt.Println(\"received signal\", sig)\u000A    default:\u000A        fmt.Println(\"no activity\")\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/number-parsing b/public/number-parsing
index 6b063ee..e222bc7 100644
--- a/public/number-parsing
+++ b/public/number-parsing
@@ -213,7 +213,7 @@ bits.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"strconv\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f, _ := strconv.ParseFloat(\"1.234\", 64)\u000A    fmt.Println(f)\u000A');codeLines.push('    i, _ := strconv.ParseInt(\"123\", 0, 64)\u000A    fmt.Println(i)\u000A');codeLines.push('    d, _ := strconv.ParseInt(\"0x1c8\", 0, 64)\u000A    fmt.Println(d)\u000A');codeLines.push('    u, _ := strconv.ParseUint(\"789\", 0, 64)\u000A    fmt.Println(u)\u000A');codeLines.push('    k, _ := strconv.Atoi(\"135\")\u000A    fmt.Println(k)\u000A');codeLines.push('    _, e := strconv.Atoi(\"wat\")\u000A    fmt.Println(e)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"strconv\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f, _ :\x3D strconv.ParseFloat(\"1.234\", 64)\u000A    fmt.Println(f)\u000A');codeLines.push('    i, _ :\x3D strconv.ParseInt(\"123\", 0, 64)\u000A    fmt.Println(i)\u000A');codeLines.push('    d, _ :\x3D strconv.ParseInt(\"0x1c8\", 0, 64)\u000A    fmt.Println(d)\u000A');codeLines.push('    u, _ :\x3D strconv.ParseUint(\"789\", 0, 64)\u000A    fmt.Println(u)\u000A');codeLines.push('    k, _ :\x3D strconv.Atoi(\"135\")\u000A    fmt.Println(k)\u000A');codeLines.push('    _, e :\x3D strconv.Atoi(\"wat\")\u000A    fmt.Println(e)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/panic b/public/panic
index f078c03..9242fcc 100644
--- a/public/panic
+++ b/public/panic
@@ -172,7 +172,7 @@ to use error-indicating return values wherever possible.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"os\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    panic(\"a problem\")\u000A');codeLines.push('    _, err := os.Create(\"/tmp/file\")\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"os\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    panic(\"a problem\")\u000A');codeLines.push('    _, err :\x3D os.Create(\"/tmp/file\")\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/pointers b/public/pointers
index 53d075a..62d3a70 100644
--- a/public/pointers
+++ b/public/pointers
@@ -193,7 +193,7 @@ the memory address for that variable.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func zeroval(ival int) {\u000A    ival = 0\u000A}\u000A');codeLines.push('func zeroptr(iptr *int) {\u000A    *iptr = 0\u000A}\u000A');codeLines.push('func main() {\u000A    i := 1\u000A    fmt.Println(\"initial:\", i)\u000A');codeLines.push('    zeroval(i)\u000A    fmt.Println(\"zeroval:\", i)\u000A');codeLines.push('    zeroptr(&i)\u000A    fmt.Println(\"zeroptr:\", i)\u000A');codeLines.push('    fmt.Println(\"pointer:\", &i)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func zeroval(ival int) {\u000A    ival \x3D 0\u000A}\u000A');codeLines.push('func zeroptr(iptr *int) {\u000A    *iptr \x3D 0\u000A}\u000A');codeLines.push('func main() {\u000A    i :\x3D 1\u000A    fmt.Println(\"initial:\", i)\u000A');codeLines.push('    zeroval(i)\u000A    fmt.Println(\"zeroval:\", i)\u000A');codeLines.push('    zeroptr(\x26i)\u000A    fmt.Println(\"zeroptr:\", i)\u000A');codeLines.push('    fmt.Println(\"pointer:\", \x26i)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/random-numbers b/public/random-numbers
index 7d14d79..39f9246 100644
--- a/public/random-numbers
+++ b/public/random-numbers
@@ -229,7 +229,7 @@ that Go can provide.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Print(rand.Intn(100), \",\")\u000A    fmt.Print(rand.Intn(100))\u000A    fmt.Println()\u000A');codeLines.push('    fmt.Println(rand.Float64())\u000A');codeLines.push('    fmt.Print((rand.Float64()*5)+5, \",\")\u000A    fmt.Print((rand.Float64() * 5) + 5)\u000A    fmt.Println()\u000A');codeLines.push('    s1 := rand.NewSource(time.Now().UnixNano())\u000A    r1 := rand.New(s1)\u000A');codeLines.push('    fmt.Print(r1.Intn(100), \",\")\u000A    fmt.Print(r1.Intn(100))\u000A    fmt.Println()\u000A');codeLines.push('    s2 := rand.NewSource(42)\u000A    r2 := rand.New(s2)\u000A    fmt.Print(r2.Intn(100), \",\")\u000A    fmt.Print(r2.Intn(100))\u000A    fmt.Println()\u000A    s3 := rand.NewSource(42)\u000A    r3 := rand.New(s3)\u000A    fmt.Print(r3.Intn(100), \",\")\u000A    fmt.Print(r3.Intn(100))\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Print(rand.Intn(100), \",\")\u000A    fmt.Print(rand.Intn(100))\u000A    fmt.Println()\u000A');codeLines.push('    fmt.Println(rand.Float64())\u000A');codeLines.push('    fmt.Print((rand.Float64()*5)+5, \",\")\u000A    fmt.Print((rand.Float64() * 5) + 5)\u000A    fmt.Println()\u000A');codeLines.push('    s1 :\x3D rand.NewSource(time.Now().UnixNano())\u000A    r1 :\x3D rand.New(s1)\u000A');codeLines.push('    fmt.Print(r1.Intn(100), \",\")\u000A    fmt.Print(r1.Intn(100))\u000A    fmt.Println()\u000A');codeLines.push('    s2 :\x3D rand.NewSource(42)\u000A    r2 :\x3D rand.New(s2)\u000A    fmt.Print(r2.Intn(100), \",\")\u000A    fmt.Print(r2.Intn(100))\u000A    fmt.Println()\u000A    s3 :\x3D rand.NewSource(42)\u000A    r3 :\x3D rand.New(s3)\u000A    fmt.Print(r3.Intn(100), \",\")\u000A    fmt.Print(r3.Intn(100))\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/range b/public/range
index 947af86..81877c9 100644
--- a/public/range
+++ b/public/range
@@ -200,7 +200,7 @@ of the <code>rune</code> and the second the <code>rune</code> itself.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    nums := []int{2, 3, 4}\u000A    sum := 0\u000A    for _, num := range nums {\u000A        sum += num\u000A    }\u000A    fmt.Println(\"sum:\", sum)\u000A');codeLines.push('    for i, num := range nums {\u000A        if num == 3 {\u000A            fmt.Println(\"index:\", i)\u000A        }\u000A    }\u000A');codeLines.push('    kvs := map[string]string{\"a\": \"apple\", \"b\": \"banana\"}\u000A    for k, v := range kvs {\u000A        fmt.Printf(\"%s -\x3E %s\\n\", k, v)\u000A    }\u000A');codeLines.push('    for k := range kvs {\u000A        fmt.Println(\"key:\", k)\u000A    }\u000A');codeLines.push('    for i, c := range \"go\" {\u000A        fmt.Println(i, c)\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    nums :\x3D []int{2, 3, 4}\u000A    sum :\x3D 0\u000A    for _, num :\x3D range nums {\u000A        sum +\x3D num\u000A    }\u000A    fmt.Println(\"sum:\", sum)\u000A');codeLines.push('    for i, num :\x3D range nums {\u000A        if num \x3D\x3D 3 {\u000A            fmt.Println(\"index:\", i)\u000A        }\u000A    }\u000A');codeLines.push('    kvs :\x3D map[string]string{\"a\": \"apple\", \"b\": \"banana\"}\u000A    for k, v :\x3D range kvs {\u000A        fmt.Printf(\"%s -\x3E %s\\n\", k, v)\u000A    }\u000A');codeLines.push('    for k :\x3D range kvs {\u000A        fmt.Println(\"key:\", k)\u000A    }\u000A');codeLines.push('    for i, c :\x3D range \"go\" {\u000A        fmt.Println(i, c)\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/range-over-channels b/public/range-over-channels
index cc279fb..6eedb6a 100644
--- a/public/range-over-channels
+++ b/public/range-over-channels
@@ -154,7 +154,7 @@ values be received.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    queue := make(chan string, 2)\u000A    queue \x3C- \"one\"\u000A    queue \x3C- \"two\"\u000A    close(queue)\u000A');codeLines.push('    for elem := range queue {\u000A        fmt.Println(elem)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    queue :\x3D make(chan string, 2)\u000A    queue \x3C- \"one\"\u000A    queue \x3C- \"two\"\u000A    close(queue)\u000A');codeLines.push('    for elem :\x3D range queue {\u000A        fmt.Println(elem)\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/rate-limiting b/public/rate-limiting
index 49e16b9..25900dd 100644
--- a/public/rate-limiting
+++ b/public/rate-limiting
@@ -261,7 +261,7 @@ then serve the remaining 2 with ~200ms delays each.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    requests := make(chan int, 5)\u000A    for i := 1; i \x3C= 5; i++ {\u000A        requests \x3C- i\u000A    }\u000A    close(requests)\u000A');codeLines.push('    limiter := time.Tick(200 * time.Millisecond)\u000A');codeLines.push('    for req := range requests {\u000A        \x3C-limiter\u000A        fmt.Println(\"request\", req, time.Now())\u000A    }\u000A');codeLines.push('    burstyLimiter := make(chan time.Time, 3)\u000A');codeLines.push('    for i := 0; i \x3C 3; i++ {\u000A        burstyLimiter \x3C- time.Now()\u000A    }\u000A');codeLines.push('    go func() {\u000A        for t := range time.Tick(200 * time.Millisecond) {\u000A            burstyLimiter \x3C- t\u000A        }\u000A    }()\u000A');codeLines.push('    burstyRequests := make(chan int, 5)\u000A    for i := 1; i \x3C= 5; i++ {\u000A        burstyRequests \x3C- i\u000A    }\u000A    close(burstyRequests)\u000A    for req := range burstyRequests {\u000A        \x3C-burstyLimiter\u000A        fmt.Println(\"request\", req, time.Now())\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    requests :\x3D make(chan int, 5)\u000A    for i :\x3D 1; i \x3C\x3D 5; i++ {\u000A        requests \x3C- i\u000A    }\u000A    close(requests)\u000A');codeLines.push('    limiter :\x3D time.Tick(200 * time.Millisecond)\u000A');codeLines.push('    for req :\x3D range requests {\u000A        \x3C-limiter\u000A        fmt.Println(\"request\", req, time.Now())\u000A    }\u000A');codeLines.push('    burstyLimiter :\x3D make(chan time.Time, 3)\u000A');codeLines.push('    for i :\x3D 0; i \x3C 3; i++ {\u000A        burstyLimiter \x3C- time.Now()\u000A    }\u000A');codeLines.push('    go func() {\u000A        for t :\x3D range time.Tick(200 * time.Millisecond) {\u000A            burstyLimiter \x3C- t\u000A        }\u000A    }()\u000A');codeLines.push('    burstyRequests :\x3D make(chan int, 5)\u000A    for i :\x3D 1; i \x3C\x3D 5; i++ {\u000A        burstyRequests \x3C- i\u000A    }\u000A    close(burstyRequests)\u000A    for req :\x3D range burstyRequests {\u000A        \x3C-burstyLimiter\u000A        fmt.Println(\"request\", req, time.Now())\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/reading-files b/public/reading-files
index 62e692c..abed995 100644
--- a/public/reading-files
+++ b/public/reading-files
@@ -287,7 +287,7 @@ be scheduled immediately after <code>Open</code>ing with
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"io\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e != nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    dat, err := ioutil.ReadFile(\"/tmp/dat\")\u000A    check(err)\u000A    fmt.Print(string(dat))\u000A');codeLines.push('    f, err := os.Open(\"/tmp/dat\")\u000A    check(err)\u000A');codeLines.push('    b1 := make([]byte, 5)\u000A    n1, err := f.Read(b1)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes: %s\\n\", n1, string(b1[:n1]))\u000A');codeLines.push('    o2, err := f.Seek(6, 0)\u000A    check(err)\u000A    b2 := make([]byte, 2)\u000A    n2, err := f.Read(b2)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes @ %d: \", n2, o2)\u000A    fmt.Printf(\"%v\\n\", string(b2[:n2]))\u000A');codeLines.push('    o3, err := f.Seek(6, 0)\u000A    check(err)\u000A    b3 := make([]byte, 2)\u000A    n3, err := io.ReadAtLeast(f, b3, 2)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes @ %d: %s\\n\", n3, o3, string(b3))\u000A');codeLines.push('    _, err = f.Seek(0, 0)\u000A    check(err)\u000A');codeLines.push('    r4 := bufio.NewReader(f)\u000A    b4, err := r4.Peek(5)\u000A    check(err)\u000A    fmt.Printf(\"5 bytes: %s\\n\", string(b4))\u000A');codeLines.push('    f.Close()\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"io\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e !\x3D nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    dat, err :\x3D ioutil.ReadFile(\"/tmp/dat\")\u000A    check(err)\u000A    fmt.Print(string(dat))\u000A');codeLines.push('    f, err :\x3D os.Open(\"/tmp/dat\")\u000A    check(err)\u000A');codeLines.push('    b1 :\x3D make([]byte, 5)\u000A    n1, err :\x3D f.Read(b1)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes: %s\\n\", n1, string(b1[:n1]))\u000A');codeLines.push('    o2, err :\x3D f.Seek(6, 0)\u000A    check(err)\u000A    b2 :\x3D make([]byte, 2)\u000A    n2, err :\x3D f.Read(b2)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes @ %d: \", n2, o2)\u000A    fmt.Printf(\"%v\\n\", string(b2[:n2]))\u000A');codeLines.push('    o3, err :\x3D f.Seek(6, 0)\u000A    check(err)\u000A    b3 :\x3D make([]byte, 2)\u000A    n3, err :\x3D io.ReadAtLeast(f, b3, 2)\u000A    check(err)\u000A    fmt.Printf(\"%d bytes @ %d: %s\\n\", n3, o3, string(b3))\u000A');codeLines.push('    _, err \x3D f.Seek(0, 0)\u000A    check(err)\u000A');codeLines.push('    r4 :\x3D bufio.NewReader(f)\u000A    b4, err :\x3D r4.Peek(5)\u000A    check(err)\u000A    fmt.Printf(\"5 bytes: %s\\n\", string(b4))\u000A');codeLines.push('    f.Close()\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/recursion b/public/recursion
index 12b7ffa..d1125aa 100644
--- a/public/recursion
+++ b/public/recursion
@@ -125,7 +125,7 @@ base case of <code>fact(0)</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func fact(n int) int {\u000A    if n == 0 {\u000A        return 1\u000A    }\u000A    return n * fact(n-1)\u000A}\u000A');codeLines.push('func main() {\u000A    fmt.Println(fact(7))\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func fact(n int) int {\u000A    if n \x3D\x3D 0 {\u000A        return 1\u000A    }\u000A    return n * fact(n-1)\u000A}\u000A');codeLines.push('func main() {\u000A    fmt.Println(fact(7))\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/regular-expressions b/public/regular-expressions
index 20d4fbd..7a312eb 100644
--- a/public/regular-expressions
+++ b/public/regular-expressions
@@ -342,7 +342,7 @@ the <a href="http://golang.org/pkg/regexp/"><code>regexp</code></a> package docs
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bytes\"\u000A    \"fmt\"\u000A    \"regexp\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    match, _ := regexp.MatchString(\"p([a-z]+)ch\", \"peach\")\u000A    fmt.Println(match)\u000A');codeLines.push('    r, _ := regexp.Compile(\"p([a-z]+)ch\")\u000A');codeLines.push('    fmt.Println(r.MatchString(\"peach\"))\u000A');codeLines.push('    fmt.Println(r.FindString(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringIndex(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringSubmatch(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringSubmatchIndex(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindAllString(\"peach punch pinch\", -1))\u000A');codeLines.push('    fmt.Println(r.FindAllStringSubmatchIndex(\u000A        \"peach punch pinch\", -1))\u000A');codeLines.push('    fmt.Println(r.FindAllString(\"peach punch pinch\", 2))\u000A');codeLines.push('    fmt.Println(r.Match([]byte(\"peach\")))\u000A');codeLines.push('    r = regexp.MustCompile(\"p([a-z]+)ch\")\u000A    fmt.Println(r)\u000A');codeLines.push('    fmt.Println(r.ReplaceAllString(\"a peach\", \"\x3Cfruit\x3E\"))\u000A');codeLines.push('    in := []byte(\"a peach\")\u000A    out := r.ReplaceAllFunc(in, bytes.ToUpper)\u000A    fmt.Println(string(out))\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bytes\"\u000A    \"fmt\"\u000A    \"regexp\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    match, _ :\x3D regexp.MatchString(\"p([a-z]+)ch\", \"peach\")\u000A    fmt.Println(match)\u000A');codeLines.push('    r, _ :\x3D regexp.Compile(\"p([a-z]+)ch\")\u000A');codeLines.push('    fmt.Println(r.MatchString(\"peach\"))\u000A');codeLines.push('    fmt.Println(r.FindString(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringIndex(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringSubmatch(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindStringSubmatchIndex(\"peach punch\"))\u000A');codeLines.push('    fmt.Println(r.FindAllString(\"peach punch pinch\", -1))\u000A');codeLines.push('    fmt.Println(r.FindAllStringSubmatchIndex(\u000A        \"peach punch pinch\", -1))\u000A');codeLines.push('    fmt.Println(r.FindAllString(\"peach punch pinch\", 2))\u000A');codeLines.push('    fmt.Println(r.Match([]byte(\"peach\")))\u000A');codeLines.push('    r \x3D regexp.MustCompile(\"p([a-z]+)ch\")\u000A    fmt.Println(r)\u000A');codeLines.push('    fmt.Println(r.ReplaceAllString(\"a peach\", \"\x3Cfruit\x3E\"))\u000A');codeLines.push('    in :\x3D []byte(\"a peach\")\u000A    out :\x3D r.ReplaceAllFunc(in, bytes.ToUpper)\u000A    fmt.Println(string(out))\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/select b/public/select
index fc1eda7..c92146f 100644
--- a/public/select
+++ b/public/select
@@ -183,7 +183,7 @@ concurrently.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    c1 := make(chan string)\u000A    c2 := make(chan string)\u000A');codeLines.push('    go func() {\u000A        time.Sleep(1 * time.Second)\u000A        c1 \x3C- \"one\"\u000A    }()\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c2 \x3C- \"two\"\u000A    }()\u000A');codeLines.push('    for i := 0; i \x3C 2; i++ {\u000A        select {\u000A        case msg1 := \x3C-c1:\u000A            fmt.Println(\"received\", msg1)\u000A        case msg2 := \x3C-c2:\u000A            fmt.Println(\"received\", msg2)\u000A        }\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    c1 :\x3D make(chan string)\u000A    c2 :\x3D make(chan string)\u000A');codeLines.push('    go func() {\u000A        time.Sleep(1 * time.Second)\u000A        c1 \x3C- \"one\"\u000A    }()\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c2 \x3C- \"two\"\u000A    }()\u000A');codeLines.push('    for i :\x3D 0; i \x3C 2; i++ {\u000A        select {\u000A        case msg1 :\x3D \x3C-c1:\u000A            fmt.Println(\"received\", msg1)\u000A        case msg2 :\x3D \x3C-c2:\u000A            fmt.Println(\"received\", msg2)\u000A        }\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/sha1-hashes b/public/sha1-hashes
index 9bbcddf..82dfb4f 100644
--- a/public/sha1-hashes
+++ b/public/sha1-hashes
@@ -203,7 +203,7 @@ you should carefully research
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"crypto/sha1\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A    s := \"sha1 this string\"\u000A');codeLines.push('    h := sha1.New()\u000A');codeLines.push('    h.Write([]byte(s))\u000A');codeLines.push('    bs := h.Sum(nil)\u000A');codeLines.push('    fmt.Println(s)\u000A    fmt.Printf(\"%x\\n\", bs)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"crypto/sha1\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A    s :\x3D \"sha1 this string\"\u000A');codeLines.push('    h :\x3D sha1.New()\u000A');codeLines.push('    h.Write([]byte(s))\u000A');codeLines.push('    bs :\x3D h.Sum(nil)\u000A');codeLines.push('    fmt.Println(s)\u000A    fmt.Printf(\"%x\\n\", bs)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/signals b/public/signals
index 786fb5a..af1a001 100644
--- a/public/signals
+++ b/public/signals
@@ -188,7 +188,7 @@ causing the program to print <code>interrupt</code> and then exit.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A    \"os/signal\"\u000A    \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    sigs := make(chan os.Signal, 1)\u000A    done := make(chan bool, 1)\u000A');codeLines.push('    signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)\u000A');codeLines.push('    go func() {\u000A        sig := \x3C-sigs\u000A        fmt.Println()\u000A        fmt.Println(sig)\u000A        done \x3C- true\u000A    }()\u000A');codeLines.push('    fmt.Println(\"awaiting signal\")\u000A    \x3C-done\u000A    fmt.Println(\"exiting\")\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A    \"os/signal\"\u000A    \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    sigs :\x3D make(chan os.Signal, 1)\u000A    done :\x3D make(chan bool, 1)\u000A');codeLines.push('    signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)\u000A');codeLines.push('    go func() {\u000A        sig :\x3D \x3C-sigs\u000A        fmt.Println()\u000A        fmt.Println(sig)\u000A        done \x3C- true\u000A    }()\u000A');codeLines.push('    fmt.Println(\"awaiting signal\")\u000A    \x3C-done\u000A    fmt.Println(\"exiting\")\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/slices b/public/slices
index c61dcb7..798a0ca 100644
--- a/public/slices
+++ b/public/slices
@@ -308,7 +308,7 @@ Go&rsquo;s other key builtin data structure: maps.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    s := make([]string, 3)\u000A    fmt.Println(\"emp:\", s)\u000A');codeLines.push('    s[0] = \"a\"\u000A    s[1] = \"b\"\u000A    s[2] = \"c\"\u000A    fmt.Println(\"set:\", s)\u000A    fmt.Println(\"get:\", s[2])\u000A');codeLines.push('    fmt.Println(\"len:\", len(s))\u000A');codeLines.push('    s = append(s, \"d\")\u000A    s = append(s, \"e\", \"f\")\u000A    fmt.Println(\"apd:\", s)\u000A');codeLines.push('    c := make([]string, len(s))\u000A    copy(c, s)\u000A    fmt.Println(\"cpy:\", c)\u000A');codeLines.push('    l := s[2:5]\u000A    fmt.Println(\"sl1:\", l)\u000A');codeLines.push('    l = s[:5]\u000A    fmt.Println(\"sl2:\", l)\u000A');codeLines.push('    l = s[2:]\u000A    fmt.Println(\"sl3:\", l)\u000A');codeLines.push('    t := []string{\"g\", \"h\", \"i\"}\u000A    fmt.Println(\"dcl:\", t)\u000A');codeLines.push('    twoD := make([][]int, 3)\u000A    for i := 0; i \x3C 3; i++ {\u000A        innerLen := i + 1\u000A        twoD[i] = make([]int, innerLen)\u000A        for j := 0; j \x3C innerLen; j++ {\u000A            twoD[i][j] = i + j\u000A        }\u000A    }\u000A    fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    s :\x3D make([]string, 3)\u000A    fmt.Println(\"emp:\", s)\u000A');codeLines.push('    s[0] \x3D \"a\"\u000A    s[1] \x3D \"b\"\u000A    s[2] \x3D \"c\"\u000A    fmt.Println(\"set:\", s)\u000A    fmt.Println(\"get:\", s[2])\u000A');codeLines.push('    fmt.Println(\"len:\", len(s))\u000A');codeLines.push('    s \x3D append(s, \"d\")\u000A    s \x3D append(s, \"e\", \"f\")\u000A    fmt.Println(\"apd:\", s)\u000A');codeLines.push('    c :\x3D make([]string, len(s))\u000A    copy(c, s)\u000A    fmt.Println(\"cpy:\", c)\u000A');codeLines.push('    l :\x3D s[2:5]\u000A    fmt.Println(\"sl1:\", l)\u000A');codeLines.push('    l \x3D s[:5]\u000A    fmt.Println(\"sl2:\", l)\u000A');codeLines.push('    l \x3D s[2:]\u000A    fmt.Println(\"sl3:\", l)\u000A');codeLines.push('    t :\x3D []string{\"g\", \"h\", \"i\"}\u000A    fmt.Println(\"dcl:\", t)\u000A');codeLines.push('    twoD :\x3D make([][]int, 3)\u000A    for i :\x3D 0; i \x3C 3; i++ {\u000A        innerLen :\x3D i + 1\u000A        twoD[i] \x3D make([]int, innerLen)\u000A        for j :\x3D 0; j \x3C innerLen; j++ {\u000A            twoD[i][j] \x3D i + j\u000A        }\u000A    }\u000A    fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/sorting b/public/sorting
index 18f89fb..e341758 100644
--- a/public/sorting
+++ b/public/sorting
@@ -160,7 +160,7 @@ slices and <code>true</code> as the result of our <code>AreSorted</code> test.</
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sort\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    strs := []string{\"c\", \"a\", \"b\"}\u000A    sort.Strings(strs)\u000A    fmt.Println(\"Strings:\", strs)\u000A');codeLines.push('    ints := []int{7, 2, 4}\u000A    sort.Ints(ints)\u000A    fmt.Println(\"Ints:   \", ints)\u000A');codeLines.push('    s := sort.IntsAreSorted(ints)\u000A    fmt.Println(\"Sorted: \", s)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sort\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    strs :\x3D []string{\"c\", \"a\", \"b\"}\u000A    sort.Strings(strs)\u000A    fmt.Println(\"Strings:\", strs)\u000A');codeLines.push('    ints :\x3D []int{7, 2, 4}\u000A    sort.Ints(ints)\u000A    fmt.Println(\"Ints:   \", ints)\u000A');codeLines.push('    s :\x3D sort.IntsAreSorted(ints)\u000A    fmt.Println(\"Sorted: \", s)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/sorting-by-functions b/public/sorting-by-functions
index 0d2b442..4f0f50e 100644
--- a/public/sorting-by-functions
+++ b/public/sorting-by-functions
@@ -177,7 +177,7 @@ functions.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sort\"\u000A)\u000A');codeLines.push('type byLength []string\u000A');codeLines.push('func (s byLength) Len() int {\u000A    return len(s)\u000A}\u000Afunc (s byLength) Swap(i, j int) {\u000A    s[i], s[j] = s[j], s[i]\u000A}\u000Afunc (s byLength) Less(i, j int) bool {\u000A    return len(s[i]) \x3C len(s[j])\u000A}\u000A');codeLines.push('func main() {\u000A    fruits := []string{\"peach\", \"banana\", \"kiwi\"}\u000A    sort.Sort(byLength(fruits))\u000A    fmt.Println(fruits)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sort\"\u000A)\u000A');codeLines.push('type byLength []string\u000A');codeLines.push('func (s byLength) Len() int {\u000A    return len(s)\u000A}\u000Afunc (s byLength) Swap(i, j int) {\u000A    s[i], s[j] \x3D s[j], s[i]\u000A}\u000Afunc (s byLength) Less(i, j int) bool {\u000A    return len(s[i]) \x3C len(s[j])\u000A}\u000A');codeLines.push('func main() {\u000A    fruits :\x3D []string{\"peach\", \"banana\", \"kiwi\"}\u000A    sort.Sort(byLength(fruits))\u000A    fmt.Println(fruits)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/spawning-processes b/public/spawning-processes
index 22aaecd..3ee9ff8 100644
--- a/public/spawning-processes
+++ b/public/spawning-processes
@@ -259,7 +259,7 @@ as if we had run them directly from the command-line.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os/exec\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    dateCmd := exec.Command(\"date\")\u000A');codeLines.push('    dateOut, err := dateCmd.Output()\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(\"\x3E date\")\u000A    fmt.Println(string(dateOut))\u000A');codeLines.push('    grepCmd := exec.Command(\"grep\", \"hello\")\u000A');codeLines.push('    grepIn, _ := grepCmd.StdinPipe()\u000A    grepOut, _ := grepCmd.StdoutPipe()\u000A    grepCmd.Start()\u000A    grepIn.Write([]byte(\"hello grep\\ngoodbye grep\"))\u000A    grepIn.Close()\u000A    grepBytes, _ := ioutil.ReadAll(grepOut)\u000A    grepCmd.Wait()\u000A');codeLines.push('    fmt.Println(\"\x3E grep hello\")\u000A    fmt.Println(string(grepBytes))\u000A');codeLines.push('    lsCmd := exec.Command(\"bash\", \"-c\", \"ls -a -l -h\")\u000A    lsOut, err := lsCmd.Output()\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(\"\x3E ls -a -l -h\")\u000A    fmt.Println(string(lsOut))\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os/exec\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    dateCmd :\x3D exec.Command(\"date\")\u000A');codeLines.push('    dateOut, err :\x3D dateCmd.Output()\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(\"\x3E date\")\u000A    fmt.Println(string(dateOut))\u000A');codeLines.push('    grepCmd :\x3D exec.Command(\"grep\", \"hello\")\u000A');codeLines.push('    grepIn, _ :\x3D grepCmd.StdinPipe()\u000A    grepOut, _ :\x3D grepCmd.StdoutPipe()\u000A    grepCmd.Start()\u000A    grepIn.Write([]byte(\"hello grep\\ngoodbye grep\"))\u000A    grepIn.Close()\u000A    grepBytes, _ :\x3D ioutil.ReadAll(grepOut)\u000A    grepCmd.Wait()\u000A');codeLines.push('    fmt.Println(\"\x3E grep hello\")\u000A    fmt.Println(string(grepBytes))\u000A');codeLines.push('    lsCmd :\x3D exec.Command(\"bash\", \"-c\", \"ls -a -l -h\")\u000A    lsOut, err :\x3D lsCmd.Output()\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(\"\x3E ls -a -l -h\")\u000A    fmt.Println(string(lsOut))\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/stateful-goroutines b/public/stateful-goroutines
index 25b8f59..88182c5 100644
--- a/public/stateful-goroutines
+++ b/public/stateful-goroutines
@@ -312,7 +312,7 @@ program.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"sync/atomic\"\u000A    \"time\"\u000A)\u000A');codeLines.push('type readOp struct {\u000A    key  int\u000A    resp chan int\u000A}\u000Atype writeOp struct {\u000A    key  int\u000A    val  int\u000A    resp chan bool\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var readOps uint64\u000A    var writeOps uint64\u000A');codeLines.push('    reads := make(chan readOp)\u000A    writes := make(chan writeOp)\u000A');codeLines.push('    go func() {\u000A        var state = make(map[int]int)\u000A        for {\u000A            select {\u000A            case read := \x3C-reads:\u000A                read.resp \x3C- state[read.key]\u000A            case write := \x3C-writes:\u000A                state[write.key] = write.val\u000A                write.resp \x3C- true\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    for r := 0; r \x3C 100; r++ {\u000A        go func() {\u000A            for {\u000A                read := readOp{\u000A                    key:  rand.Intn(5),\u000A                    resp: make(chan int)}\u000A                reads \x3C- read\u000A                \x3C-read.resp\u000A                atomic.AddUint64(&readOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    for w := 0; w \x3C 10; w++ {\u000A        go func() {\u000A            for {\u000A                write := writeOp{\u000A                    key:  rand.Intn(5),\u000A                    val:  rand.Intn(100),\u000A                    resp: make(chan bool)}\u000A                writes \x3C- write\u000A                \x3C-write.resp\u000A                atomic.AddUint64(&writeOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    time.Sleep(time.Second)\u000A');codeLines.push('    readOpsFinal := atomic.LoadUint64(&readOps)\u000A    fmt.Println(\"readOps:\", readOpsFinal)\u000A    writeOpsFinal := atomic.LoadUint64(&writeOps)\u000A    fmt.Println(\"writeOps:\", writeOpsFinal)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"math/rand\"\u000A    \"sync/atomic\"\u000A    \"time\"\u000A)\u000A');codeLines.push('type readOp struct {\u000A    key  int\u000A    resp chan int\u000A}\u000Atype writeOp struct {\u000A    key  int\u000A    val  int\u000A    resp chan bool\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var readOps uint64\u000A    var writeOps uint64\u000A');codeLines.push('    reads :\x3D make(chan readOp)\u000A    writes :\x3D make(chan writeOp)\u000A');codeLines.push('    go func() {\u000A        var state \x3D make(map[int]int)\u000A        for {\u000A            select {\u000A            case read :\x3D \x3C-reads:\u000A                read.resp \x3C- state[read.key]\u000A            case write :\x3D \x3C-writes:\u000A                state[write.key] \x3D write.val\u000A                write.resp \x3C- true\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    for r :\x3D 0; r \x3C 100; r++ {\u000A        go func() {\u000A            for {\u000A                read :\x3D readOp{\u000A                    key:  rand.Intn(5),\u000A                    resp: make(chan int)}\u000A                reads \x3C- read\u000A                \x3C-read.resp\u000A                atomic.AddUint64(\x26readOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    for w :\x3D 0; w \x3C 10; w++ {\u000A        go func() {\u000A            for {\u000A                write :\x3D writeOp{\u000A                    key:  rand.Intn(5),\u000A                    val:  rand.Intn(100),\u000A                    resp: make(chan bool)}\u000A                writes \x3C- write\u000A                \x3C-write.resp\u000A                atomic.AddUint64(\x26writeOps, 1)\u000A                time.Sleep(time.Millisecond)\u000A            }\u000A        }()\u000A    }\u000A');codeLines.push('    time.Sleep(time.Second)\u000A');codeLines.push('    readOpsFinal :\x3D atomic.LoadUint64(\x26readOps)\u000A    fmt.Println(\"readOps:\", readOpsFinal)\u000A    writeOpsFinal :\x3D atomic.LoadUint64(\x26writeOps)\u000A    fmt.Println(\"writeOps:\", writeOpsFinal)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/string-formatting b/public/string-formatting
index 6ec0568..5c1f574 100644
--- a/public/string-formatting
+++ b/public/string-formatting
@@ -457,7 +457,7 @@ and returns a string without printing it anywhere.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('type point struct {\u000A    x, y int\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p := point{1, 2}\u000A    fmt.Printf(\"%v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%+v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%#v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%T\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%t\\n\", true)\u000A');codeLines.push('    fmt.Printf(\"%d\\n\", 123)\u000A');codeLines.push('    fmt.Printf(\"%b\\n\", 14)\u000A');codeLines.push('    fmt.Printf(\"%c\\n\", 33)\u000A');codeLines.push('    fmt.Printf(\"%x\\n\", 456)\u000A');codeLines.push('    fmt.Printf(\"%f\\n\", 78.9)\u000A');codeLines.push('    fmt.Printf(\"%e\\n\", 123400000.0)\u000A    fmt.Printf(\"%E\\n\", 123400000.0)\u000A');codeLines.push('    fmt.Printf(\"%s\\n\", \"\\\"string\\\"\")\u000A');codeLines.push('    fmt.Printf(\"%q\\n\", \"\\\"string\\\"\")\u000A');codeLines.push('    fmt.Printf(\"%x\\n\", \"hex this\")\u000A');codeLines.push('    fmt.Printf(\"%p\\n\", &p)\u000A');codeLines.push('    fmt.Printf(\"|%6d|%6d|\\n\", 12, 345)\u000A');codeLines.push('    fmt.Printf(\"|%6.2f|%6.2f|\\n\", 1.2, 3.45)\u000A');codeLines.push('    fmt.Printf(\"|%-6.2f|%-6.2f|\\n\", 1.2, 3.45)\u000A');codeLines.push('    fmt.Printf(\"|%6s|%6s|\\n\", \"foo\", \"b\")\u000A');codeLines.push('    fmt.Printf(\"|%-6s|%-6s|\\n\", \"foo\", \"b\")\u000A');codeLines.push('    s := fmt.Sprintf(\"a %s\", \"string\")\u000A    fmt.Println(s)\u000A');codeLines.push('    fmt.Fprintf(os.Stderr, \"an %s\\n\", \"error\")\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"os\"\u000A)\u000A');codeLines.push('type point struct {\u000A    x, y int\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p :\x3D point{1, 2}\u000A    fmt.Printf(\"%v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%+v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%#v\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%T\\n\", p)\u000A');codeLines.push('    fmt.Printf(\"%t\\n\", true)\u000A');codeLines.push('    fmt.Printf(\"%d\\n\", 123)\u000A');codeLines.push('    fmt.Printf(\"%b\\n\", 14)\u000A');codeLines.push('    fmt.Printf(\"%c\\n\", 33)\u000A');codeLines.push('    fmt.Printf(\"%x\\n\", 456)\u000A');codeLines.push('    fmt.Printf(\"%f\\n\", 78.9)\u000A');codeLines.push('    fmt.Printf(\"%e\\n\", 123400000.0)\u000A    fmt.Printf(\"%E\\n\", 123400000.0)\u000A');codeLines.push('    fmt.Printf(\"%s\\n\", \"\\\"string\\\"\")\u000A');codeLines.push('    fmt.Printf(\"%q\\n\", \"\\\"string\\\"\")\u000A');codeLines.push('    fmt.Printf(\"%x\\n\", \"hex this\")\u000A');codeLines.push('    fmt.Printf(\"%p\\n\", \x26p)\u000A');codeLines.push('    fmt.Printf(\"|%6d|%6d|\\n\", 12, 345)\u000A');codeLines.push('    fmt.Printf(\"|%6.2f|%6.2f|\\n\", 1.2, 3.45)\u000A');codeLines.push('    fmt.Printf(\"|%-6.2f|%-6.2f|\\n\", 1.2, 3.45)\u000A');codeLines.push('    fmt.Printf(\"|%6s|%6s|\\n\", \"foo\", \"b\")\u000A');codeLines.push('    fmt.Printf(\"|%-6s|%-6s|\\n\", \"foo\", \"b\")\u000A');codeLines.push('    s :\x3D fmt.Sprintf(\"a %s\", \"string\")\u000A    fmt.Println(s)\u000A');codeLines.push('    fmt.Fprintf(os.Stderr, \"an %s\\n\", \"error\")\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/string-functions b/public/string-functions
index 3c0ddfa..f486976 100644
--- a/public/string-functions
+++ b/public/string-functions
@@ -209,7 +209,7 @@ for more information.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    s \"strings\"\u000A)\u000A');codeLines.push('var p = fmt.Println\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p(\"Contains:  \", s.Contains(\"test\", \"es\"))\u000A    p(\"Count:     \", s.Count(\"test\", \"t\"))\u000A    p(\"HasPrefix: \", s.HasPrefix(\"test\", \"te\"))\u000A    p(\"HasSuffix: \", s.HasSuffix(\"test\", \"st\"))\u000A    p(\"Index:     \", s.Index(\"test\", \"e\"))\u000A    p(\"Join:      \", s.Join([]string{\"a\", \"b\"}, \"-\"))\u000A    p(\"Repeat:    \", s.Repeat(\"a\", 5))\u000A    p(\"Replace:   \", s.Replace(\"foo\", \"o\", \"0\", -1))\u000A    p(\"Replace:   \", s.Replace(\"foo\", \"o\", \"0\", 1))\u000A    p(\"Split:     \", s.Split(\"a-b-c-d-e\", \"-\"))\u000A    p(\"ToLower:   \", s.ToLower(\"TEST\"))\u000A    p(\"ToUpper:   \", s.ToUpper(\"test\"))\u000A    p()\u000A');codeLines.push('    p(\"Len: \", len(\"hello\"))\u000A    p(\"Char:\", \"hello\"[1])\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    s \"strings\"\u000A)\u000A');codeLines.push('var p \x3D fmt.Println\u000A');codeLines.push('func main() {\u000A');codeLines.push('    p(\"Contains:  \", s.Contains(\"test\", \"es\"))\u000A    p(\"Count:     \", s.Count(\"test\", \"t\"))\u000A    p(\"HasPrefix: \", s.HasPrefix(\"test\", \"te\"))\u000A    p(\"HasSuffix: \", s.HasSuffix(\"test\", \"st\"))\u000A    p(\"Index:     \", s.Index(\"test\", \"e\"))\u000A    p(\"Join:      \", s.Join([]string{\"a\", \"b\"}, \"-\"))\u000A    p(\"Repeat:    \", s.Repeat(\"a\", 5))\u000A    p(\"Replace:   \", s.Replace(\"foo\", \"o\", \"0\", -1))\u000A    p(\"Replace:   \", s.Replace(\"foo\", \"o\", \"0\", 1))\u000A    p(\"Split:     \", s.Split(\"a-b-c-d-e\", \"-\"))\u000A    p(\"ToLower:   \", s.ToLower(\"TEST\"))\u000A    p(\"ToUpper:   \", s.ToUpper(\"test\"))\u000A    p()\u000A');codeLines.push('    p(\"Len: \", len(\"hello\"))\u000A    p(\"Char:\", \"hello\"[1])\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/structs b/public/structs
index e941fef..26dfab3 100644
--- a/public/structs
+++ b/public/structs
@@ -266,7 +266,7 @@ pointers are automatically dereferenced.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('type person struct {\u000A    name string\u000A    age  int\u000A}\u000A');codeLines.push('func NewPerson(name string) *person {\u000A');codeLines.push('    p := person{name: name}\u000A    p.age = 42\u000A    return &p\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Println(person{\"Bob\", 20})\u000A');codeLines.push('    fmt.Println(person{name: \"Alice\", age: 30})\u000A');codeLines.push('    fmt.Println(person{name: \"Fred\"})\u000A');codeLines.push('    fmt.Println(&person{name: \"Ann\", age: 40})\u000A');codeLines.push('    fmt.Println(NewPerson(\"Jon\"))\u000A');codeLines.push('    s := person{name: \"Sean\", age: 50}\u000A    fmt.Println(s.name)\u000A');codeLines.push('    sp := &s\u000A    fmt.Println(sp.age)\u000A');codeLines.push('    sp.age = 51\u000A    fmt.Println(sp.age)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('type person struct {\u000A    name string\u000A    age  int\u000A}\u000A');codeLines.push('func NewPerson(name string) *person {\u000A');codeLines.push('    p :\x3D person{name: name}\u000A    p.age \x3D 42\u000A    return \x26p\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Println(person{\"Bob\", 20})\u000A');codeLines.push('    fmt.Println(person{name: \"Alice\", age: 30})\u000A');codeLines.push('    fmt.Println(person{name: \"Fred\"})\u000A');codeLines.push('    fmt.Println(\x26person{name: \"Ann\", age: 40})\u000A');codeLines.push('    fmt.Println(NewPerson(\"Jon\"))\u000A');codeLines.push('    s :\x3D person{name: \"Sean\", age: 50}\u000A    fmt.Println(s.name)\u000A');codeLines.push('    sp :\x3D \x26s\u000A    fmt.Println(sp.age)\u000A');codeLines.push('    sp.age \x3D 51\u000A    fmt.Println(sp.age)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/switch b/public/switch
index ead4de4..3cf0fc6 100644
--- a/public/switch
+++ b/public/switch
@@ -203,7 +203,7 @@ type corresponding to its clause.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    i := 2\u000A    fmt.Print(\"Write \", i, \" as \")\u000A    switch i {\u000A    case 1:\u000A        fmt.Println(\"one\")\u000A    case 2:\u000A        fmt.Println(\"two\")\u000A    case 3:\u000A        fmt.Println(\"three\")\u000A    }\u000A');codeLines.push('    switch time.Now().Weekday() {\u000A    case time.Saturday, time.Sunday:\u000A        fmt.Println(\"It\'s the weekend\")\u000A    default:\u000A        fmt.Println(\"It\'s a weekday\")\u000A    }\u000A');codeLines.push('    t := time.Now()\u000A    switch {\u000A    case t.Hour() \x3C 12:\u000A        fmt.Println(\"It\'s before noon\")\u000A    default:\u000A        fmt.Println(\"It\'s after noon\")\u000A    }\u000A');codeLines.push('    whatAmI := func(i interface{}) {\u000A        switch t := i.(type) {\u000A        case bool:\u000A            fmt.Println(\"I\'m a bool\")\u000A        case int:\u000A            fmt.Println(\"I\'m an int\")\u000A        default:\u000A            fmt.Printf(\"Don\'t know type %T\\n\", t)\u000A        }\u000A    }\u000A    whatAmI(true)\u000A    whatAmI(1)\u000A    whatAmI(\"hey\")\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    i :\x3D 2\u000A    fmt.Print(\"Write \", i, \" as \")\u000A    switch i {\u000A    case 1:\u000A        fmt.Println(\"one\")\u000A    case 2:\u000A        fmt.Println(\"two\")\u000A    case 3:\u000A        fmt.Println(\"three\")\u000A    }\u000A');codeLines.push('    switch time.Now().Weekday() {\u000A    case time.Saturday, time.Sunday:\u000A        fmt.Println(\"It\'s the weekend\")\u000A    default:\u000A        fmt.Println(\"It\'s a weekday\")\u000A    }\u000A');codeLines.push('    t :\x3D time.Now()\u000A    switch {\u000A    case t.Hour() \x3C 12:\u000A        fmt.Println(\"It\'s before noon\")\u000A    default:\u000A        fmt.Println(\"It\'s after noon\")\u000A    }\u000A');codeLines.push('    whatAmI :\x3D func(i interface{}) {\u000A        switch t :\x3D i.(type) {\u000A        case bool:\u000A            fmt.Println(\"I\'m a bool\")\u000A        case int:\u000A            fmt.Println(\"I\'m an int\")\u000A        default:\u000A            fmt.Printf(\"Don\'t know type %T\\n\", t)\u000A        }\u000A    }\u000A    whatAmI(true)\u000A    whatAmI(1)\u000A    whatAmI(\"hey\")\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/temporary-files-and-directories b/public/temporary-files-and-directories
index 3919f36..346ae74 100644
--- a/public/temporary-files-and-directories
+++ b/public/temporary-files-and-directories
@@ -241,7 +241,7 @@ prefixing them with our temporary directory.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A    \"path/filepath\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e != nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f, err := ioutil.TempFile(\"\", \"sample\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Temp file name:\", f.Name())\u000A');codeLines.push('    defer os.Remove(f.Name())\u000A');codeLines.push('    _, err = f.Write([]byte{1, 2, 3, 4})\u000A    check(err)\u000A');codeLines.push('    dname, err := ioutil.TempDir(\"\", \"sampledir\")\u000A    fmt.Println(\"Temp dir name:\", dname)\u000A');codeLines.push('    defer os.RemoveAll(dname)\u000A');codeLines.push('    fname := filepath.Join(dname, \"file1\")\u000A    err = ioutil.WriteFile(fname, []byte{1, 2}, 0666)\u000A    check(err)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A    \"path/filepath\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e !\x3D nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    f, err :\x3D ioutil.TempFile(\"\", \"sample\")\u000A    check(err)\u000A');codeLines.push('    fmt.Println(\"Temp file name:\", f.Name())\u000A');codeLines.push('    defer os.Remove(f.Name())\u000A');codeLines.push('    _, err \x3D f.Write([]byte{1, 2, 3, 4})\u000A    check(err)\u000A');codeLines.push('    dname, err :\x3D ioutil.TempDir(\"\", \"sampledir\")\u000A    fmt.Println(\"Temp dir name:\", dname)\u000A');codeLines.push('    defer os.RemoveAll(dname)\u000A');codeLines.push('    fname :\x3D filepath.Join(dname, \"file1\")\u000A    err \x3D ioutil.WriteFile(fname, []byte{1, 2}, 0666)\u000A    check(err)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/testing b/public/testing
index e8a3bc2..6b0a3aa 100644
--- a/public/testing
+++ b/public/testing
@@ -232,7 +232,7 @@ when executing <code>go test -v</code>.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"testing\"\u000A)\u000A');codeLines.push('func IntMin(a, b int) int {\u000A    if a \x3C b {\u000A        return a\u000A    } else {\u000A        return b\u000A    }\u000A}\u000A');codeLines.push('func TestIntMinBasic(t *testing.T) {\u000A    ans := IntMin(2, -2)\u000A    if ans != -2 {\u000A');codeLines.push('        t.Errorf(\"IntMin(2, -2) = %d; want -2\", ans)\u000A    }\u000A}\u000A');codeLines.push('func TestIntMinTableDriven(t *testing.T) {\u000A    var tests = []struct {\u000A        a, b int\u000A        want int\u000A    }{\u000A        {0, 1, 0},\u000A        {1, 0, 0},\u000A        {2, -2, -2},\u000A        {0, -1, -1},\u000A        {-1, 0, -1},\u000A    }\u000A');codeLines.push('    for _, tt := range tests {\u000A');codeLines.push('        testname := fmt.Sprintf(\"%d,%d\", tt.a, tt.b)\u000A        t.Run(testname, func(t *testing.T) {\u000A            ans := IntMin(tt.a, tt.b)\u000A            if ans != tt.want {\u000A                t.Errorf(\"got %d, want %d\", ans, tt.want)\u000A            }\u000A        })\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"testing\"\u000A)\u000A');codeLines.push('func IntMin(a, b int) int {\u000A    if a \x3C b {\u000A        return a\u000A    } else {\u000A        return b\u000A    }\u000A}\u000A');codeLines.push('func TestIntMinBasic(t *testing.T) {\u000A    ans :\x3D IntMin(2, -2)\u000A    if ans !\x3D -2 {\u000A');codeLines.push('        t.Errorf(\"IntMin(2, -2) \x3D %d; want -2\", ans)\u000A    }\u000A}\u000A');codeLines.push('func TestIntMinTableDriven(t *testing.T) {\u000A    var tests \x3D []struct {\u000A        a, b int\u000A        want int\u000A    }{\u000A        {0, 1, 0},\u000A        {1, 0, 0},\u000A        {2, -2, -2},\u000A        {0, -1, -1},\u000A        {-1, 0, -1},\u000A    }\u000A');codeLines.push('    for _, tt :\x3D range tests {\u000A');codeLines.push('        testname :\x3D fmt.Sprintf(\"%d,%d\", tt.a, tt.b)\u000A        t.Run(testname, func(t *testing.T) {\u000A            ans :\x3D IntMin(tt.a, tt.b)\u000A            if ans !\x3D tt.want {\u000A                t.Errorf(\"got %d, want %d\", ans, tt.want)\u000A            }\u000A        })\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/tickers b/public/tickers
index 6b219ab..aa0fac7 100644
--- a/public/tickers
+++ b/public/tickers
@@ -171,7 +171,7 @@ before we stop it.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    ticker := time.NewTicker(500 * time.Millisecond)\u000A    done := make(chan bool)\u000A');codeLines.push('    go func() {\u000A        for {\u000A            select {\u000A            case \x3C-done:\u000A                return\u000A            case t := \x3C-ticker.C:\u000A                fmt.Println(\"Tick at\", t)\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    time.Sleep(1600 * time.Millisecond)\u000A    ticker.Stop()\u000A    done \x3C- true\u000A    fmt.Println(\"Ticker stopped\")\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    ticker :\x3D time.NewTicker(500 * time.Millisecond)\u000A    done :\x3D make(chan bool)\u000A');codeLines.push('    go func() {\u000A        for {\u000A            select {\u000A            case \x3C-done:\u000A                return\u000A            case t :\x3D \x3C-ticker.C:\u000A                fmt.Println(\"Tick at\", t)\u000A            }\u000A        }\u000A    }()\u000A');codeLines.push('    time.Sleep(1600 * time.Millisecond)\u000A    ticker.Stop()\u000A    done \x3C- true\u000A    fmt.Println(\"Ticker stopped\")\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/time b/public/time
index ae80469..246ffa8 100644
--- a/public/time
+++ b/public/time
@@ -270,7 +270,7 @@ the Unix epoch.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A    p := fmt.Println\u000A');codeLines.push('    now := time.Now()\u000A    p(now)\u000A');codeLines.push('    then := time.Date(\u000A        2009, 11, 17, 20, 34, 58, 651387237, time.UTC)\u000A    p(then)\u000A');codeLines.push('    p(then.Year())\u000A    p(then.Month())\u000A    p(then.Day())\u000A    p(then.Hour())\u000A    p(then.Minute())\u000A    p(then.Second())\u000A    p(then.Nanosecond())\u000A    p(then.Location())\u000A');codeLines.push('    p(then.Weekday())\u000A');codeLines.push('    p(then.Before(now))\u000A    p(then.After(now))\u000A    p(then.Equal(now))\u000A');codeLines.push('    diff := now.Sub(then)\u000A    p(diff)\u000A');codeLines.push('    p(diff.Hours())\u000A    p(diff.Minutes())\u000A    p(diff.Seconds())\u000A    p(diff.Nanoseconds())\u000A');codeLines.push('    p(then.Add(diff))\u000A    p(then.Add(-diff))\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A    p :\x3D fmt.Println\u000A');codeLines.push('    now :\x3D time.Now()\u000A    p(now)\u000A');codeLines.push('    then :\x3D time.Date(\u000A        2009, 11, 17, 20, 34, 58, 651387237, time.UTC)\u000A    p(then)\u000A');codeLines.push('    p(then.Year())\u000A    p(then.Month())\u000A    p(then.Day())\u000A    p(then.Hour())\u000A    p(then.Minute())\u000A    p(then.Second())\u000A    p(then.Nanosecond())\u000A    p(then.Location())\u000A');codeLines.push('    p(then.Weekday())\u000A');codeLines.push('    p(then.Before(now))\u000A    p(then.After(now))\u000A    p(then.Equal(now))\u000A');codeLines.push('    diff :\x3D now.Sub(then)\u000A    p(diff)\u000A');codeLines.push('    p(diff.Hours())\u000A    p(diff.Minutes())\u000A    p(diff.Seconds())\u000A    p(diff.Nanoseconds())\u000A');codeLines.push('    p(then.Add(diff))\u000A    p(then.Add(-diff))\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/time-formatting-parsing b/public/time-formatting-parsing
index e6b54d8..6e7fbcb 100644
--- a/public/time-formatting-parsing
+++ b/public/time-formatting-parsing
@@ -204,7 +204,7 @@ explaining the parsing problem.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A    p := fmt.Println\u000A');codeLines.push('    t := time.Now()\u000A    p(t.Format(time.RFC3339))\u000A');codeLines.push('    t1, e := time.Parse(\u000A        time.RFC3339,\u000A        \"2012-11-01T22:08:41+00:00\")\u000A    p(t1)\u000A');codeLines.push('    p(t.Format(\"3:04PM\"))\u000A    p(t.Format(\"Mon Jan _2 15:04:05 2006\"))\u000A    p(t.Format(\"2006-01-02T15:04:05.999999-07:00\"))\u000A    form := \"3 04 PM\"\u000A    t2, e := time.Parse(form, \"8 41 PM\")\u000A    p(t2)\u000A');codeLines.push('    fmt.Printf(\"%d-%02d-%02dT%02d:%02d:%02d-00:00\\n\",\u000A        t.Year(), t.Month(), t.Day(),\u000A        t.Hour(), t.Minute(), t.Second())\u000A');codeLines.push('    ansic := \"Mon Jan _2 15:04:05 2006\"\u000A    _, e = time.Parse(ansic, \"8:41PM\")\u000A    p(e)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A    p :\x3D fmt.Println\u000A');codeLines.push('    t :\x3D time.Now()\u000A    p(t.Format(time.RFC3339))\u000A');codeLines.push('    t1, e :\x3D time.Parse(\u000A        time.RFC3339,\u000A        \"2012-11-01T22:08:41+00:00\")\u000A    p(t1)\u000A');codeLines.push('    p(t.Format(\"3:04PM\"))\u000A    p(t.Format(\"Mon Jan _2 15:04:05 2006\"))\u000A    p(t.Format(\"2006-01-02T15:04:05.999999-07:00\"))\u000A    form :\x3D \"3 04 PM\"\u000A    t2, e :\x3D time.Parse(form, \"8 41 PM\")\u000A    p(t2)\u000A');codeLines.push('    fmt.Printf(\"%d-%02d-%02dT%02d:%02d:%02d-00:00\\n\",\u000A        t.Year(), t.Month(), t.Day(),\u000A        t.Hour(), t.Minute(), t.Second())\u000A');codeLines.push('    ansic :\x3D \"Mon Jan _2 15:04:05 2006\"\u000A    _, e \x3D time.Parse(ansic, \"8:41PM\")\u000A    p(e)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/timeouts b/public/timeouts
index 36abd54..0d1854d 100644
--- a/public/timeouts
+++ b/public/timeouts
@@ -181,7 +181,7 @@ out and the second succeeding.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    c1 := make(chan string, 1)\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c1 \x3C- \"result 1\"\u000A    }()\u000A');codeLines.push('    select {\u000A    case res := \x3C-c1:\u000A        fmt.Println(res)\u000A    case \x3C-time.After(1 * time.Second):\u000A        fmt.Println(\"timeout 1\")\u000A    }\u000A');codeLines.push('    c2 := make(chan string, 1)\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c2 \x3C- \"result 2\"\u000A    }()\u000A    select {\u000A    case res := \x3C-c2:\u000A        fmt.Println(res)\u000A    case \x3C-time.After(3 * time.Second):\u000A        fmt.Println(\"timeout 2\")\u000A    }\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    c1 :\x3D make(chan string, 1)\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c1 \x3C- \"result 1\"\u000A    }()\u000A');codeLines.push('    select {\u000A    case res :\x3D \x3C-c1:\u000A        fmt.Println(res)\u000A    case \x3C-time.After(1 * time.Second):\u000A        fmt.Println(\"timeout 1\")\u000A    }\u000A');codeLines.push('    c2 :\x3D make(chan string, 1)\u000A    go func() {\u000A        time.Sleep(2 * time.Second)\u000A        c2 \x3C- \"result 2\"\u000A    }()\u000A    select {\u000A    case res :\x3D \x3C-c2:\u000A        fmt.Println(res)\u000A    case \x3C-time.After(3 * time.Second):\u000A        fmt.Println(\"timeout 2\")\u000A    }\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/timers b/public/timers
index 6f79311..4e75368 100644
--- a/public/timers
+++ b/public/timers
@@ -184,7 +184,7 @@ a chance to fire.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    timer1 := time.NewTimer(2 * time.Second)\u000A');codeLines.push('    \x3C-timer1.C\u000A    fmt.Println(\"Timer 1 fired\")\u000A');codeLines.push('    timer2 := time.NewTimer(time.Second)\u000A    go func() {\u000A        \x3C-timer2.C\u000A        fmt.Println(\"Timer 2 fired\")\u000A    }()\u000A    stop2 := timer2.Stop()\u000A    if stop2 {\u000A        fmt.Println(\"Timer 2 stopped\")\u000A    }\u000A');codeLines.push('    time.Sleep(2 * time.Second)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    timer1 :\x3D time.NewTimer(2 * time.Second)\u000A');codeLines.push('    \x3C-timer1.C\u000A    fmt.Println(\"Timer 1 fired\")\u000A');codeLines.push('    timer2 :\x3D time.NewTimer(time.Second)\u000A    go func() {\u000A        \x3C-timer2.C\u000A        fmt.Println(\"Timer 2 fired\")\u000A    }()\u000A    stop2 :\x3D timer2.Stop()\u000A    if stop2 {\u000A        fmt.Println(\"Timer 2 stopped\")\u000A    }\u000A');codeLines.push('    time.Sleep(2 * time.Second)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/url-parsing b/public/url-parsing
index 4fd0fb8..cb70ac7 100644
--- a/public/url-parsing
+++ b/public/url-parsing
@@ -235,7 +235,7 @@ pieces that we extracted.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net\"\u000A    \"net/url\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    s := \"postgres://user:pass@host.com:5432/path?k=v#f\"\u000A');codeLines.push('    u, err := url.Parse(s)\u000A    if err != nil {\u000A        panic(err)\u000A    }\u000A');codeLines.push('    fmt.Println(u.Scheme)\u000A');codeLines.push('    fmt.Println(u.User)\u000A    fmt.Println(u.User.Username())\u000A    p, _ := u.User.Password()\u000A    fmt.Println(p)\u000A');codeLines.push('    fmt.Println(u.Host)\u000A    host, port, _ := net.SplitHostPort(u.Host)\u000A    fmt.Println(host)\u000A    fmt.Println(port)\u000A');codeLines.push('    fmt.Println(u.Path)\u000A    fmt.Println(u.Fragment)\u000A');codeLines.push('    fmt.Println(u.RawQuery)\u000A    m, _ := url.ParseQuery(u.RawQuery)\u000A    fmt.Println(m)\u000A    fmt.Println(m[\"k\"][0])\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"net\"\u000A    \"net/url\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push('    s :\x3D \"postgres://user:pass@host.com:5432/path?k\x3Dv#f\"\u000A');codeLines.push('    u, err :\x3D url.Parse(s)\u000A    if err !\x3D nil {\u000A        panic(err)\u000A    }\u000A');codeLines.push('    fmt.Println(u.Scheme)\u000A');codeLines.push('    fmt.Println(u.User)\u000A    fmt.Println(u.User.Username())\u000A    p, _ :\x3D u.User.Password()\u000A    fmt.Println(p)\u000A');codeLines.push('    fmt.Println(u.Host)\u000A    host, port, _ :\x3D net.SplitHostPort(u.Host)\u000A    fmt.Println(host)\u000A    fmt.Println(port)\u000A');codeLines.push('    fmt.Println(u.Path)\u000A    fmt.Println(u.Fragment)\u000A');codeLines.push('    fmt.Println(u.RawQuery)\u000A    m, _ :\x3D url.ParseQuery(u.RawQuery)\u000A    fmt.Println(m)\u000A    fmt.Println(m[\"k\"][0])\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/values b/public/values
index 807830b..aee60a2 100644
--- a/public/values
+++ b/public/values
@@ -152,7 +152,7 @@ basic examples.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Println(\"go\" + \"lang\")\u000A');codeLines.push('    fmt.Println(\"1+1 =\", 1+1)\u000A    fmt.Println(\"7.0/3.0 =\", 7.0/3.0)\u000A');codeLines.push('    fmt.Println(true && false)\u000A    fmt.Println(true || false)\u000A    fmt.Println(!true)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    fmt.Println(\"go\" + \"lang\")\u000A');codeLines.push('    fmt.Println(\"1+1 \x3D\", 1+1)\u000A    fmt.Println(\"7.0/3.0 \x3D\", 7.0/3.0)\u000A');codeLines.push('    fmt.Println(true \x26\x26 false)\u000A    fmt.Println(true || false)\u000A    fmt.Println(!true)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/variables b/public/variables
index b10cded..312b5e5 100644
--- a/public/variables
+++ b/public/variables
@@ -183,7 +183,7 @@ initializing a variable, e.g. for
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var a = \"initial\"\u000A    fmt.Println(a)\u000A');codeLines.push('    var b, c int = 1, 2\u000A    fmt.Println(b, c)\u000A');codeLines.push('    var d = true\u000A    fmt.Println(d)\u000A');codeLines.push('    var e int\u000A    fmt.Println(e)\u000A');codeLines.push('    f := \"apple\"\u000A    fmt.Println(f)\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var a \x3D \"initial\"\u000A    fmt.Println(a)\u000A');codeLines.push('    var b, c int \x3D 1, 2\u000A    fmt.Println(b, c)\u000A');codeLines.push('    var d \x3D true\u000A    fmt.Println(d)\u000A');codeLines.push('    var e int\u000A    fmt.Println(e)\u000A');codeLines.push('    f :\x3D \"apple\"\u000A    fmt.Println(f)\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/variadic-functions b/public/variadic-functions
index d366658..0ce77f5 100644
--- a/public/variadic-functions
+++ b/public/variadic-functions
@@ -172,7 +172,7 @@ to form closures, which we&rsquo;ll look at next.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func sum(nums ...int) {\u000A    fmt.Print(nums, \" \")\u000A    total := 0\u000A    for _, num := range nums {\u000A        total += num\u000A    }\u000A    fmt.Println(total)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    sum(1, 2)\u000A    sum(1, 2, 3)\u000A');codeLines.push('    nums := []int{1, 2, 3, 4}\u000A    sum(nums...)\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func sum(nums ...int) {\u000A    fmt.Print(nums, \" \")\u000A    total :\x3D 0\u000A    for _, num :\x3D range nums {\u000A        total +\x3D num\u000A    }\u000A    fmt.Println(total)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    sum(1, 2)\u000A    sum(1, 2, 3)\u000A');codeLines.push('    nums :\x3D []int{1, 2, 3, 4}\u000A    sum(nums...)\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/waitgroups b/public/waitgroups
index e47765d..85856ce 100644
--- a/public/waitgroups
+++ b/public/waitgroups
@@ -229,7 +229,7 @@ is likely to be different for each invocation.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, wg *sync.WaitGroup) {\u000A');codeLines.push('    defer wg.Done()\u000A');codeLines.push('    fmt.Printf(\"Worker %d starting\\n\", id)\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Printf(\"Worker %d done\\n\", id)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i := 1; i \x3C= 5; i++ {\u000A        wg.Add(1)\u000A        go worker(i, &wg)\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"sync\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, wg *sync.WaitGroup) {\u000A');codeLines.push('    defer wg.Done()\u000A');codeLines.push('    fmt.Printf(\"Worker %d starting\\n\", id)\u000A');codeLines.push('    time.Sleep(time.Second)\u000A    fmt.Printf(\"Worker %d done\\n\", id)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    var wg sync.WaitGroup\u000A');codeLines.push('    for i :\x3D 1; i \x3C\x3D 5; i++ {\u000A        wg.Add(1)\u000A        go worker(i, \x26wg)\u000A    }\u000A');codeLines.push('    wg.Wait()\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/worker-pools b/public/worker-pools
index 0b7c7d1..e7fec32 100644
--- a/public/worker-pools
+++ b/public/worker-pools
@@ -224,7 +224,7 @@ there are 3 workers operating concurrently.</p>
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, jobs \x3C-chan int, results chan\x3C- int) {\u000A    for j := range jobs {\u000A        fmt.Println(\"worker\", id, \"started  job\", j)\u000A        time.Sleep(time.Second)\u000A        fmt.Println(\"worker\", id, \"finished job\", j)\u000A        results \x3C- j * 2\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    const numJobs = 5\u000A    jobs := make(chan int, numJobs)\u000A    results := make(chan int, numJobs)\u000A');codeLines.push('    for w := 1; w \x3C= 3; w++ {\u000A        go worker(w, jobs, results)\u000A    }\u000A');codeLines.push('    for j := 1; j \x3C= numJobs; j++ {\u000A        jobs \x3C- j\u000A    }\u000A    close(jobs)\u000A');codeLines.push('    for a := 1; a \x3C= numJobs; a++ {\u000A        \x3C-results\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(id int, jobs \x3C-chan int, results chan\x3C- int) {\u000A    for j :\x3D range jobs {\u000A        fmt.Println(\"worker\", id, \"started  job\", j)\u000A        time.Sleep(time.Second)\u000A        fmt.Println(\"worker\", id, \"finished job\", j)\u000A        results \x3C- j * 2\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    const numJobs \x3D 5\u000A    jobs :\x3D make(chan int, numJobs)\u000A    results :\x3D make(chan int, numJobs)\u000A');codeLines.push('    for w :\x3D 1; w \x3C\x3D 3; w++ {\u000A        go worker(w, jobs, results)\u000A    }\u000A');codeLines.push('    for j :\x3D 1; j \x3C\x3D numJobs; j++ {\u000A        jobs \x3C- j\u000A    }\u000A    close(jobs)\u000A');codeLines.push('    for a :\x3D 1; a \x3C\x3D numJobs; a++ {\u000A        \x3C-results\u000A    }\u000A}\u000A');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/writing-files b/public/writing-files
index 49214e1..6d0626c 100644
--- a/public/writing-files
+++ b/public/writing-files
@@ -287,7 +287,7 @@ we&rsquo;ve just seen to the <code>stdin</code> and <code>stdout</code> streams.
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e != nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    d1 := []byte(\"hello\\ngo\\n\")\u000A    err := ioutil.WriteFile(\"/tmp/dat1\", d1, 0644)\u000A    check(err)\u000A');codeLines.push('    f, err := os.Create(\"/tmp/dat2\")\u000A    check(err)\u000A');codeLines.push('    defer f.Close()\u000A');codeLines.push('    d2 := []byte{115, 111, 109, 101, 10}\u000A    n2, err := f.Write(d2)\u000A    check(err)\u000A    fmt.Printf(\"wrote %d bytes\\n\", n2)\u000A');codeLines.push('    n3, err := f.WriteString(\"writes\\n\")\u000A    fmt.Printf(\"wrote %d bytes\\n\", n3)\u000A');codeLines.push('    f.Sync()\u000A');codeLines.push('    w := bufio.NewWriter(f)\u000A    n4, err := w.WriteString(\"buffered\\n\")\u000A    fmt.Printf(\"wrote %d bytes\\n\", n4)\u000A');codeLines.push('    w.Flush()\u000A');codeLines.push('}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"bufio\"\u000A    \"fmt\"\u000A    \"io/ioutil\"\u000A    \"os\"\u000A)\u000A');codeLines.push('func check(e error) {\u000A    if e !\x3D nil {\u000A        panic(e)\u000A    }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    d1 :\x3D []byte(\"hello\\ngo\\n\")\u000A    err :\x3D ioutil.WriteFile(\"/tmp/dat1\", d1, 0644)\u000A    check(err)\u000A');codeLines.push('    f, err :\x3D os.Create(\"/tmp/dat2\")\u000A    check(err)\u000A');codeLines.push('    defer f.Close()\u000A');codeLines.push('    d2 :\x3D []byte{115, 111, 109, 101, 10}\u000A    n2, err :\x3D f.Write(d2)\u000A    check(err)\u000A    fmt.Printf(\"wrote %d bytes\\n\", n2)\u000A');codeLines.push('    n3, err :\x3D f.WriteString(\"writes\\n\")\u000A    fmt.Printf(\"wrote %d bytes\\n\", n3)\u000A');codeLines.push('    f.Sync()\u000A');codeLines.push('    w :\x3D bufio.NewWriter(f)\u000A    n4, err :\x3D w.WriteString(\"buffered\\n\")\u000A    fmt.Printf(\"wrote %d bytes\\n\", n4)\u000A');codeLines.push('    w.Flush()\u000A');codeLines.push('}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>
diff --git a/public/xml b/public/xml
index 85a2d15..66f7c5a 100644
--- a/public/xml
+++ b/public/xml
@@ -281,7 +281,7 @@ to nest all <code>plant</code>s under <code>&lt;parent&gt;&lt;child&gt;...</code
     </div>
     <script>
       var codeLines = [];
-      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"encoding/xml\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('type Plant struct {\u000A    XMLName xml.Name `xml:\"plant\"`\u000A    Id      int      `xml:\"id,attr\"`\u000A    Name    string   `xml:\"name\"`\u000A    Origin  []string `xml:\"origin\"`\u000A}\u000A');codeLines.push('func (p Plant) String() string {\u000A    return fmt.Sprintf(\"Plant id=%v, name=%v, origin=%v\",\u000A        p.Id, p.Name, p.Origin)\u000A}\u000A');codeLines.push('func main() {\u000A    coffee := &Plant{Id: 27, Name: \"Coffee\"}\u000A    coffee.Origin = []string{\"Ethiopia\", \"Brazil\"}\u000A');codeLines.push('    out, _ := xml.MarshalIndent(coffee, \" \", \"  \")\u000A    fmt.Println(string(out))\u000A');codeLines.push('    fmt.Println(xml.Header + string(out))\u000A');codeLines.push('    var p Plant\u000A    if err := xml.Unmarshal(out, &p); err != nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(p)\u000A');codeLines.push('    tomato := &Plant{Id: 81, Name: \"Tomato\"}\u000A    tomato.Origin = []string{\"Mexico\", \"California\"}\u000A');codeLines.push('    type Nesting struct {\u000A        XMLName xml.Name `xml:\"nesting\"`\u000A        Plants  []*Plant `xml:\"parent\x3Echild\x3Eplant\"`\u000A    }\u000A');codeLines.push('    nesting := &Nesting{}\u000A    nesting.Plants = []*Plant{coffee, tomato}\u000A');codeLines.push('    out, _ = xml.MarshalIndent(nesting, \" \", \"  \")\u000A    fmt.Println(string(out))\u000A}\u000A');codeLines.push('');
+      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"encoding/xml\"\u000A    \"fmt\"\u000A)\u000A');codeLines.push('type Plant struct {\u000A    XMLName xml.Name `xml:\"plant\"`\u000A    Id      int      `xml:\"id,attr\"`\u000A    Name    string   `xml:\"name\"`\u000A    Origin  []string `xml:\"origin\"`\u000A}\u000A');codeLines.push('func (p Plant) String() string {\u000A    return fmt.Sprintf(\"Plant id\x3D%v, name\x3D%v, origin\x3D%v\",\u000A        p.Id, p.Name, p.Origin)\u000A}\u000A');codeLines.push('func main() {\u000A    coffee :\x3D \x26Plant{Id: 27, Name: \"Coffee\"}\u000A    coffee.Origin \x3D []string{\"Ethiopia\", \"Brazil\"}\u000A');codeLines.push('    out, _ :\x3D xml.MarshalIndent(coffee, \" \", \"  \")\u000A    fmt.Println(string(out))\u000A');codeLines.push('    fmt.Println(xml.Header + string(out))\u000A');codeLines.push('    var p Plant\u000A    if err :\x3D xml.Unmarshal(out, \x26p); err !\x3D nil {\u000A        panic(err)\u000A    }\u000A    fmt.Println(p)\u000A');codeLines.push('    tomato :\x3D \x26Plant{Id: 81, Name: \"Tomato\"}\u000A    tomato.Origin \x3D []string{\"Mexico\", \"California\"}\u000A');codeLines.push('    type Nesting struct {\u000A        XMLName xml.Name `xml:\"nesting\"`\u000A        Plants  []*Plant `xml:\"parent\x3Echild\x3Eplant\"`\u000A    }\u000A');codeLines.push('    nesting :\x3D \x26Nesting{}\u000A    nesting.Plants \x3D []*Plant{coffee, tomato}\u000A');codeLines.push('    out, _ \x3D xml.MarshalIndent(nesting, \" \", \"  \")\u000A    fmt.Println(string(out))\u000A}\u000A');codeLines.push('');
     </script>
     <script src="site.js" async></script>
   </body>