docs: function ReadableSerialOrdered(list, iterator, sortMethod, callback)
  {
    if (!(this instanceof ReadableSerialOrdered))
    {
      return new ReadableSerialOrdered(list, iterator, sortMethod, callback);
    }
  
    // turn on object mode
    ReadableSerialOrdered.super_.call(this, {objectMode: true});
  
    this._start(serialOrdered, list, iterator, sortMethod, callback);
  }