Add more comments to the code

letUtils.nim

@@ -116,22 +116,22 @@ macro freezeVars*(body: untyped): auto =
 
         validate thing
   ]##
-  let letTuple = nnkVarTuple.newNimNode
-  let varTupleConstr = nnkTupleConstr.newNimNode
+  let letTuple = nnkVarTuple.newNimNode # To be assigned outside `body`.
+  let varTupleConstr = nnkTupleConstr.newNimNode # Forwarded from inside.
 
   func recurse(body: NimNode) =
     for node in body:
-      case node.kind
-      of nnkVarSection:
-        for defs in node:
-          for i in 0 ..< defs.len - 2:
-            let varIdent = defs[i]
-            letTuple.add varIdent
-            varTupleConstr.add varIdent
-      of nnkStmtList:
-        node.recurse
-      else:
-        discard
+      case node.kind:
+        of nnkVarSection:
+          for defs in node:
+            for i in 0 ..< defs.len - 2:
+              let varIdent = defs[i]
+              letTuple.add varIdent
+              varTupleConstr.add varIdent
+        of nnkStmtList: # `body` can have nested statement lists if was generated by a macro.
+          node.recurse
+        else:
+          discard
 
   body.expectKind nnkStmtList
   body.recurse