code: def create_track(self, path_in_ipod=None, checksum=None):
          
          if bool(path_in_ipod) == bool(checksum):
              raise Exception
  
          if not path_in_ipod:
              path_in_ipod = self.audiodb.get_voice(checksum)
  
          track = Track(self, path_in_ipod=path_in_ipod)
  
          return track
docs: :param path_in_ipod: the path of audio file in the iPod base
          :param checksum: CHECKSUM of the audio file in member audiodb
          :return: a new Track, you may want append it to the playlist.tracks