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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 off(self):
 """Turn off the alsa_sink sink. This disconnects the sink from the relevant session events. """

        spotifyconnect._session_instance.player.off(
            spotifyconnect.PlayerEvent.MUSIC_DELIVERY, self._on_music_delivery)
        assert spotifyconnect._session_instance.player.num_listeners(
            spotifyconnect.PlayerEvent.MUSIC_DELIVERY) == 0
        self._close()