code: function watchStream(callback) {
      if (!_.isFunction(callback)) {
          callback = function() {};
      }
  
      return through.obj(function(chunk, enc, cb) {
          var webpackOptions = chunk[propsStream.FIELD_NAME] || {},
              compilerOptions = chunk[initStream.FIELD_NAME] || {},
              adapter = new CompilerAdapter(compilerOptions, webpackOptions);
  
          gutil.log(MESSAGE, gutil.colors.magenta(tildify(chunk.path)));
  
          adapter.watch(chunk, function(err, stats) {
              callback.apply(chunk, [err, stats]);
          });
  
          cb();
      });
  }
docs: Accepts `webpack.config.js` files via `gulp.src()`, then compiles via `webpack.watch()`. Re-emits all data passed from `webpack.watch()`. Can be piped.
  **Note**: Needs to be used after `webpack.init()` and `webpack.props()`.
  @function
  @alias watchStream
  @param {compilationCallback=} callback
  @returns {Stream}