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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_mode(self, playmode):
 """Set the speaker's mode."""

        playmode = playmode.upper()
        if playmode not in PLAY_MODES.keys():
            raise KeyError("'%s' is not a valid play mode" % playmode)

        self.avTransport.SetPlayMode([
            ('InstanceID', 0),
            ('NewPlayMode', playmode)
        ])