Merge pull request #11 from svetley1/patch-1

* Example of non-enumerable fields

Author: DzyubSpirit

JavaScript/4-for-in-obj.js

@@ -9,6 +9,11 @@ const hash = {
 
 hash.fifth = 2;
 
+Object.defineProperty(hash, 'newField', {
+  enumerable: false,
+  value: 'valueOfNewField',
+});
+
 for (const key in hash) {
   const value = hash[key];
   console.log(