So siehts ganz gut aus !

node_modules/es5-ext/object/ensure-natural-number.js

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