diff --git a/028-pointers.go b/027-pointers.go
similarity index 100%
rename from 028-pointers.go
rename to 027-pointers.go
diff --git a/029-new.go b/028-new.go
similarity index 100%
rename from 029-new.go
rename to 028-new.go
diff --git a/030-structs.go b/029-structs.go
similarity index 100%
rename from 030-structs.go
rename to 029-structs.go
diff --git a/031-fields.go b/030-fields.go
similarity index 100%
rename from 031-fields.go
rename to 030-fields.go
diff --git a/032-methods.go b/031-methods.go
similarity index 100%
rename from 032-methods.go
rename to 031-methods.go
diff --git a/033-embedding.go b/032-embedding.go
similarity index 100%
rename from 033-embedding.go
rename to 032-embedding.go
diff --git a/034-interfaces.go b/033-interfaces.go
similarity index 100%
rename from 034-interfaces.go
rename to 033-interfaces.go
diff --git a/035-goroutines.go b/034-goroutines.go
similarity index 100%
rename from 035-goroutines.go
rename to 034-goroutines.go
diff --git a/036-concurrency.go b/035-concurrency.go
similarity index 100%
rename from 036-concurrency.go
rename to 035-concurrency.go
diff --git a/037-channels.go b/036-channels.go
similarity index 100%
rename from 037-channels.go
rename to 036-channels.go
diff --git a/038-buffering.go b/037-buffering.go
similarity index 100%
rename from 038-buffering.go
rename to 037-buffering.go
diff --git a/039-directions.go b/038-directions.go
similarity index 100%
rename from 039-directions.go
rename to 038-directions.go
diff --git a/040-synchronization.go b/039-synchronization.go
similarity index 100%
rename from 040-synchronization.go
rename to 039-synchronization.go
diff --git a/041-select.go b/040-select.go
similarity index 100%
rename from 041-select.go
rename to 040-select.go
diff --git a/042-timeout.go b/041-timeout.go
similarity index 100%
rename from 042-timeout.go
rename to 041-timeout.go
diff --git a/043-string-fns.go b/042-string-fns.go
similarity index 100%
rename from 043-string-fns.go
rename to 042-string-fns.go
diff --git a/044-bytes.go b/043-bytes.go
similarity index 100%
rename from 044-bytes.go
rename to 043-bytes.go
diff --git a/045-args.go b/044-args.go
similarity index 100%
rename from 045-args.go
rename to 044-args.go
diff --git a/046-burstable-rate-limiting.go b/045-burstable-rate-limiting.go
similarity index 100%
rename from 046-burstable-rate-limiting.go
rename to 045-burstable-rate-limiting.go
diff --git a/047-dns.go b/046-dns.go
similarity index 100%
rename from 047-dns.go
rename to 046-dns.go
diff --git a/048-elapsed.go b/047-elapsed.go
similarity index 100%
rename from 048-elapsed.go
rename to 047-elapsed.go
diff --git a/049-email.go b/048-email.go
similarity index 100%
rename from 049-email.go
rename to 048-email.go
diff --git a/050-enumerable.go b/049-enumerable.go
similarity index 100%
rename from 050-enumerable.go
rename to 049-enumerable.go
diff --git a/051-env.go b/050-env.go
similarity index 100%
rename from 051-env.go
rename to 050-env.go
diff --git a/052-epoch.go b/051-epoch.go
similarity index 100%
rename from 052-epoch.go
rename to 051-epoch.go
diff --git a/053-errors.go b/052-errors.go
similarity index 100%
rename from 053-errors.go
rename to 052-errors.go
diff --git a/054-exec.go b/053-exec.go
similarity index 100%
rename from 054-exec.go
rename to 053-exec.go
diff --git a/054-exit.go b/054-exit.go
new file mode 100644
index 0000000..ddfad46
--- /dev/null
+++ b/054-exit.go
@@ -0,0 +1,21 @@
+package main            // Use `os.Exit` to immediatly exit with a given
+                        // status.
+import  "os"
+
+func main() {
+    defer println("!")  // This `println` will never be reached.
+	os.Exit(3)  
+}
+
+/*
+$ go run exit.go        // If you run `exit.go` using `go run`, the exit
+exit status 3           // will be picked up by `go` and printed.
+                        
+$ go build exit.go      // By building and executing a binary you can see
+$ ./exit                // the status in the terminal
+$ echo $?
+3
+*/
+
+// == todo
+// discuss building before getting here
diff --git a/055-exits.go b/055-exits.go
deleted file mode 100644
index 0d37cc9..0000000
--- a/055-exits.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package main
-
-import "os"
-
-func main() {
-	os.Exit(3)
-}
-
-// $ go run xx-exit.go
-// exit status 3
-// $ go build xx-exit.go
-// $ ./xx-exit
-// $ echo $?
-// 3
diff --git a/056-file-open.go b/055-file-open.go
similarity index 100%
rename from 056-file-open.go
rename to 055-file-open.go
diff --git a/057-file-read.go b/056-file-read.go
similarity index 100%
rename from 057-file-read.go
rename to 056-file-read.go
diff --git a/058-file-write.go b/057-file-write.go
similarity index 100%
rename from 058-file-write.go
rename to 057-file-write.go
diff --git a/059-flags.go b/058-flags.go
similarity index 100%
rename from 059-flags.go
rename to 058-flags.go
diff --git a/060-http-client-basic.go b/059-http-client-basic.go
similarity index 100%
rename from 060-http-client-basic.go
rename to 059-http-client-basic.go
diff --git a/061-http-client.go b/060-http-client.go
similarity index 100%
rename from 061-http-client.go
rename to 060-http-client.go
diff --git a/062-http-server-basic.go b/061-http-server-basic.go
similarity index 100%
rename from 062-http-server-basic.go
rename to 061-http-server-basic.go
diff --git a/063-http-server-canonical-host.go b/062-http-server-canonical-host.go
similarity index 100%
rename from 063-http-server-canonical-host.go
rename to 062-http-server-canonical-host.go
diff --git a/064-http-server-graceful-shutdown.go b/063-http-server-graceful-shutdown.go
similarity index 100%
rename from 064-http-server-graceful-shutdown.go
rename to 063-http-server-graceful-shutdown.go
diff --git a/065-http-server-log.go b/064-http-server-log.go
similarity index 100%
rename from 065-http-server-log.go
rename to 064-http-server-log.go
diff --git a/066-http-server-middleware.go b/065-http-server-middleware.go
similarity index 100%
rename from 066-http-server-middleware.go
rename to 065-http-server-middleware.go
diff --git a/067-http-server-routing.go b/066-http-server-routing.go
similarity index 100%
rename from 067-http-server-routing.go
rename to 066-http-server-routing.go
diff --git a/068-http-server-static-dynamic.go b/067-http-server-static-dynamic.go
similarity index 100%
rename from 068-http-server-static-dynamic.go
rename to 067-http-server-static-dynamic.go
diff --git a/069-http-server-static-select.go b/068-http-server-static-select.go
similarity index 100%
rename from 069-http-server-static-select.go
rename to 068-http-server-static-select.go
diff --git a/070-http-server-static.go b/069-http-server-static.go
similarity index 100%
rename from 070-http-server-static.go
rename to 069-http-server-static.go
diff --git a/071-http-server-status-code.go b/070-http-server-status-code.go
similarity index 100%
rename from 071-http-server-status-code.go
rename to 070-http-server-status-code.go
diff --git a/072-http-server.go b/071-http-server.go
similarity index 100%
rename from 072-http-server.go
rename to 071-http-server.go
diff --git a/073-https-client.go b/072-https-client.go
similarity index 100%
rename from 073-https-client.go
rename to 072-https-client.go
diff --git a/074-https-server.go b/073-https-server.go
similarity index 100%
rename from 074-https-server.go
rename to 073-https-server.go
diff --git a/075-json.go b/074-json.go
similarity index 100%
rename from 075-json.go
rename to 074-json.go
diff --git a/076-number-parsing.go b/075-number-parsing.go
similarity index 100%
rename from 076-number-parsing.go
rename to 075-number-parsing.go
diff --git a/077-postgres.go b/076-postgres.go
similarity index 100%
rename from 077-postgres.go
rename to 076-postgres.go
diff --git a/078-rand.go b/077-rand.go
similarity index 100%
rename from 078-rand.go
rename to 077-rand.go
diff --git a/079-rate-limiting.go b/078-rate-limiting.go
similarity index 100%
rename from 079-rate-limiting.go
rename to 078-rate-limiting.go
diff --git a/080-redis.go b/079-redis.go
similarity index 100%
rename from 080-redis.go
rename to 079-redis.go
diff --git a/081-regexs.go b/080-regexs.go
similarity index 100%
rename from 081-regexs.go
rename to 080-regexs.go
diff --git a/082-scatter-gather.go b/081-scatter-gather.go
similarity index 100%
rename from 082-scatter-gather.go
rename to 081-scatter-gather.go
diff --git a/083-sha1.go b/082-sha1.go
similarity index 100%
rename from 083-sha1.go
rename to 082-sha1.go
diff --git a/084-signals.go b/083-signals.go
similarity index 100%
rename from 084-signals.go
rename to 083-signals.go
diff --git a/085-sort.go b/084-sort.go
similarity index 100%
rename from 085-sort.go
rename to 084-sort.go
diff --git a/086-sortby.go b/085-sortby.go
similarity index 100%
rename from 086-sortby.go
rename to 085-sortby.go
diff --git a/087-spawn.go b/086-spawn.go
similarity index 100%
rename from 087-spawn.go
rename to 086-spawn.go
diff --git a/088-string-formatting.go b/087-string-formatting.go
similarity index 100%
rename from 088-string-formatting.go
rename to 087-string-formatting.go
diff --git a/089-tcp-client.go b/088-tcp-client.go
similarity index 100%
rename from 089-tcp-client.go
rename to 088-tcp-client.go
diff --git a/090-tcp-server.go b/089-tcp-server.go
similarity index 100%
rename from 090-tcp-server.go
rename to 089-tcp-server.go
diff --git a/091-tickers.go b/090-tickers.go
similarity index 100%
rename from 091-tickers.go
rename to 090-tickers.go
diff --git a/092-time.go b/091-time.go
similarity index 100%
rename from 092-time.go
rename to 091-time.go
diff --git a/093-timers.go b/092-timers.go
similarity index 100%
rename from 093-timers.go
rename to 092-timers.go
diff --git a/094-url.go b/093-url.go
similarity index 100%
rename from 094-url.go
rename to 093-url.go
diff --git a/095-users.go b/094-users.go
similarity index 100%
rename from 095-users.go
rename to 094-users.go
diff --git a/096-worker-pool.go b/095-worker-pool.go
similarity index 100%
rename from 096-worker-pool.go
rename to 095-worker-pool.go
diff --git a/tool/index.txt b/tool/index.txt
index 9d90a66..301dcd9 100644
--- a/tool/index.txt
+++ b/tool/index.txt
@@ -24,7 +24,6 @@ recursion
 defer
 panic
 recover
-values
 pointers
 new
 structs
@@ -52,7 +51,7 @@ env
 epoch
 errors
 exec
-exits
+exit
 file-open
 file-read
 file-write
diff --git a/tool/renumber.go b/tool/renumber.go
index 2b6ac10..c62f756 100644
--- a/tool/renumber.go
+++ b/tool/renumber.go
@@ -9,8 +9,16 @@ import (
     "strings"
     "regexp"
     "os"
+    "sort"
 )
 
+func minInt(a, b int) int {
+    if (a < b) {
+        return a
+    }
+    return b
+}
+
 func main() {
     // read names of source files
     sourceNames := make([]string, 0)
@@ -33,7 +41,12 @@ func main() {
     
     // sanity check two lists
     if len(sourceNames) != len(indexNames) {
-        panic("mismatched names")
+        sort.Strings(sourceNames)
+        sort.Strings(indexNames)
+        for i := 0; i < minInt(len(sourceNames), len(indexNames)); i++ {
+            fmt.Printf("%s %s\n", sourceNames[i], indexNames[i])
+        }
+        os.Exit(1)
     }
     
     // rename some stuff