Izmjenjena struktura, dodan backand

web/node_modules/es5-ext/function/valid-function.js

@@ -0,0 +1,8 @@
+"use strict";
+
+var isFunction = require("./is-function");
+
+module.exports = function (value) {
+	if (!isFunction(value)) throw new TypeError(value + " is not a function");
+	return value;
+};