added unit testing, and started implementing unit tests...phew

node_modules/async/internal/doLimit.js

@@ -0,0 +1,12 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = doLimit;
+function doLimit(fn, limit) {
+    return function (iterable, iteratee, callback) {
+        return fn(iterable, limit, iteratee, callback);
+    };
+}
+module.exports = exports["default"];