added whole system from ola4doc

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

@@ -0,0 +1,9 @@
+'use strict';
+
+var isNatural = require('../number/is-natural');
+
+module.exports = function (arg) {
+	var num = Number(arg);
+	if (!isNatural(num)) throw new TypeError(arg + " is not a natural number");
+	return num;
+};