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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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()