improved gulpfile

src/Buffer.js

@@ -1,14 +1,18 @@
 /* @flow */
+/* global Buffer */
 
-class Buffer {
+class Buffer { //eslint-disable-line no-unused-vars
   i : number;
   constructor () {
     this.i = 4;
   }
 }
 
+
 function add(x : string){
   return x + 4;
 }
 
+
 add("5");
+add("6");

src/y.js

@@ -1,4 +1,4 @@
 /* @flow */
 /* global Buffer */
 
-var buffer = new Buffer(3);
+export default Buffer;