Turn on the alsa_sink sink.

        This is done automatically when the sink is instantiated, so you'll
        only need to call this method if you ever call :meth:`off` and want to
        turn the sink back on.

def on(self):
        """Turn on the alsa_sink sink.

        This is done automatically when the sink is instantiated, so you'll
        only need to call this method if you ever call :meth:`off` and want to
        turn the sink back on.
        """
        assert spotifyconnect._session_instance.player.num_listeners(
            spotifyconnect.PlayerEvent.MUSIC_DELIVERY) == 0
        spotifyconnect._session_instance.player.on(
            spotifyconnect.PlayerEvent.MUSIC_DELIVERY, self._on_music_delivery)