diff --git a/lib/6to5/traverse/index.js b/lib/6to5/traverse/index.js
index 2d411d1a5a..a6fe9c1efe 100644
--- a/lib/6to5/traverse/index.js
+++ b/lib/6to5/traverse/index.js
@@ -2,8 +2,10 @@ var VISITOR_KEYS = require("./visitor-keys");
 var _            = require("lodash");
 
 var traverse = module.exports = function (parent, callbacks, blacklistTypes) {
+  // falsy node
   if (!parent) return;
 
+  // array of nodes
   if (_.isArray(parent)) {
     _.each(parent, function (node) {
       traverse(node, callbacks, blacklistTypes);
@@ -11,14 +13,15 @@ var traverse = module.exports = function (parent, callbacks, blacklistTypes) {
     return;
   }
 
+  // unknown node type to traverse
   var keys = VISITOR_KEYS[parent.type];
   if (!keys) return;
 
+  // blacklist these node types from being traversed
   blacklistTypes = blacklistTypes || [];
 
-  if (_.isFunction(callbacks)) {
-    callbacks = { enter: callbacks };
-  }
+  // normalise callbacks
+  if (_.isFunction(callbacks)) callbacks = { enter: callbacks };
 
   _.each(keys, function (key) {
     var nodes = parent[key];
@@ -87,11 +90,15 @@ traverse.hasType = function (tree, type, blacklistTypes) {
   var has = false;
 
   if (_.isArray(tree)) {
+    // array of nodes, find the first
     return !!_.find(tree, function (node) {
       return traverse.hasType(node, type, blacklistTypes);
     });
   } else {
+    // the node we're searching in is blacklisted
     if (_.contains(blacklistTypes, tree.type)) return false;
+
+    // the type we're looking for is the same as the passed node
     if (tree.type === type) return true;
 
     traverse(tree, function (node) {