install gulp to process code

node_modules/vinyl-fs/lib/src/prepare.js

@@ -0,0 +1,24 @@
+'use strict';
+
+var Transform = require('streamx').Transform;
+
+function prepareRead(optResolver) {
+  function normalize(file, callback) {
+    var since = optResolver.resolve('since', file);
+
+    if (file.stat) {
+      // Skip this file if since option is set and current file is too old
+      if (Math.max(file.stat.mtime, file.stat.ctime) <= since) {
+        return callback();
+      }
+    }
+
+    return callback(null, file);
+  }
+
+  return new Transform({
+    transform: normalize,
+  });
+}
+
+module.exports = prepareRead;