before we try this

tool/index.txt

@@ -1,10 +1,10 @@
+# basics
 hello-world
 values
 variables
 mutation
 literals
 constants
-reading-input
 for
 if-else
 case
@@ -14,7 +14,6 @@ range
 floats
 slices
 maps
-ok-guards
 nesting
 functions
 returns
@@ -31,6 +30,10 @@ fields
 methods
 embedding
 interfaces
+ok-guards
+errors
+
+# concurrency
 goroutines
 concurrency
 channels
@@ -39,24 +42,58 @@ directions
 synchronization
 select
 timeouts
-string-functions
-bytes
-command-line-arguments
+scatter-gather
+rate-limiting
 burstable-rate-limiting
-elapsed
-email
-enumerable
-env
+worker-pool
+
+# core libraries
+sort
+sort-by-function
+string-functions
+string-formatting
+regexs
+bytes
+json
+sha1-hashes
+time
 epoch
-errors
-exec
-exit
+elapsed
+timers
+tickers
+rand
+number-parsing
+enumerable
+urls
+
+# systems
 file-open
 file-read
 file-write
+command-line-arguments
 command-line-flags
-http-client-basic
+env
+signals
+exit
+spawn
+exec
+reading-input
+users
+line-filter
+
+# network clients
+tcp-client
 http-client
+http-client-basic
+https-client
+redis
+postgres
+email
+
+# network servers
+tcp-server
+
+# web apps
 http-server-basic
 http-server-canonical-host
 http-server-graceful-shutdown
@@ -68,28 +105,4 @@ http-server-static-select
 http-server-static
 http-server-status-code
 http-server
-https-client
 https-server
-json
-number-parsing
-postgres
-rand
-rate-limiting
-redis
-regexs
-scatter-gather
-sha1-hashes
-signals
-sort
-sort-by-function
-spawn
-string-formatting
-tcp-client
-tcp-server
-tickers
-time
-timers
-urls
-users
-worker-pool
-line-filter

tool/renumber.go

@@ -37,7 +37,13 @@ func main() {
     // read names from index
     indexBytes, idxErr := ioutil.ReadFile("tool/index.txt")
     if idxErr != nil { panic (idxErr) }
-    indexNames := strings.Split(string(indexBytes), "\n")
+    indexNamesAll := strings.Split(string(indexBytes), "\n")
+    indexNames := make([]string, 0)
+    for _, indexName := range indexNamesAll {
+        if (indexName !=) "" && !(indexName.Contains("#")) {
+            indexNames := append(indexNames, indexName)
+        }
+    }
     
     // sanity check two lists
     if len(sourceNames) != len(indexNames) {