install gulp to process code

node_modules/collect-stream/index.js

@@ -0,0 +1,15 @@
+import { default as concat } from 'concat-stream';
+import { default as once } from 'once';
+
+export default function collect(stream, opts, fn) {
+  if (typeof opts === 'function') {
+    fn = opts;
+    opts = {};
+  }
+  fn = once(fn);
+  stream.on('error', fn);
+  stream.pipe(concat(opts, data => {
+    fn(null, data);
+  }));
+};
+