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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 transpose(self, semitone):
 """ Transpose the pianorolls of all tracks by a number of semitones, where positive values are for higher key, while negative values are for lower key. The drum tracks are ignored. Parameters semitone : int The number of semitones to transpose the pianorolls. """

        for track in self.tracks:
            if not track.is_drum:
                track.transpose(semitone)