docs: function onEvent (watcher) {
      // Wait for write stream to end if write has been delayed.
      if (writeDelayed) { return undefined; }
  
      // If any watch events occur while writing to dest then restart
      // write stream with new changes.
      if (stream.isWriting()) {
          writeDelayed = true;
  
          stream.endWriteStream();
      // Initial write of files to dest.
      } else {
          writeStartTime = Date.now();
  
          writeFiles();
      }
  }