Added the underscore node_module.

node_modules/underscore/modules/_createAssigner.js

@@ -0,0 +1,18 @@
+// An internal function for creating assigner functions.
+export default function createAssigner(keysFunc, defaults) {
+  return function(obj) {
+    var length = arguments.length;
+    if (defaults) obj = Object(obj);
+    if (length < 2 || obj == null) return obj;
+    for (var index = 1; index < length; index++) {
+      var source = arguments[index],
+          keys = keysFunc(source),
+          l = keys.length;
+      for (var i = 0; i < l; i++) {
+        var key = keys[i];
+        if (!defaults || obj[key] === void 0) obj[key] = source[key];
+      }
+    }
+    return obj;
+  };
+}