diff --git a/src/loader.prefix b/src/loader.prefix
index 9c199e92931c..d4ff4e4dcd47 100644
--- a/src/loader.prefix
+++ b/src/loader.prefix
@@ -5,3 +5,4 @@
  */
 'use strict';
 (function() {
+    function isFunction(value) {return typeof value === 'function';};
\ No newline at end of file