docs: def play_async(cls, file_path, on_done=None):
          """ Play an audio file asynchronously.
  
          :param file_path: the path to the file to play.
          :param on_done: callback when audio playback completes.
          """
          thread = threading.Thread(
              target=AudioPlayer.play, args=(file_path, on_done,))
          thread.start()