code: function (stream, destPath) {
      let data = '';
      return new Promise(function (resolve, reject) {
          stream.on('error', reject);
          stream.on('data', function (d) {
              data += d.toString();
          });
          stream.on('end', function () {
              fs.outputFile(destPath, data, function (err) {
                  if (!err) {
                      resolve();
                  } else {
                      reject(err);
                  }
              });
          });
      });
  }
docs: Handles writing the browserify bundle stream to the destination file.
  @param {EventEmitter} stream - The bundle stream
  @param {string} destPath - The destination file
  @private