added whole system from ola4doc

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

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