install gulp to process code

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

@@ -0,0 +1,30 @@
+'use strict';
+
+var Transform = require('streamx').Transform;
+var sourcemap = require('vinyl-sourcemap');
+
+function sourcemapStream(optResolver) {
+  function addSourcemap(file, callback) {
+    var srcMap = optResolver.resolve('sourcemaps', file);
+
+    if (!srcMap) {
+      return callback(null, file);
+    }
+
+    sourcemap.add(file, onAdd);
+
+    function onAdd(sourcemapErr, updatedFile) {
+      if (sourcemapErr) {
+        return callback(sourcemapErr);
+      }
+
+      callback(null, updatedFile);
+    }
+  }
+
+  return new Transform({
+    transform: addSourcemap,
+  });
+}
+
+module.exports = sourcemapStream;