code: function update () {
        sourceOrOptions.bundle()
          .pipe(concat(function (data) {
            add(filepath, data.toString())
          }))
          .on('error', function (err) {
            console.error(err.stack)
            ASSET_PENDING--
          })
      }
docs: If the source look-like a browserify/watchify bundler we use it as a ressource updater