install gulp

user/themes/anissabensalah/node_modules/es5-ext/object/ensure-natural-number-value.js

@@ -0,0 +1,10 @@
+"use strict";
+
+var isNaturalValue = require("./is-natural-number-value")
+  , toShortString  = require("../to-short-string-representation");
+
+module.exports = function (arg) {
+	var num = Number(arg);
+	if (!isNaturalValue(arg)) throw new TypeError(toShortString(arg) + " is not a natural number");
+	return num;
+};