code: def get_active_pitch_range(self):
          
          lowest, highest = self.tracks[0].get_active_pitch_range()
          if len(self.tracks) > 1:
              for track in self.tracks[1:]:
                  low, high = track.get_active_pitch_range()
                  if low < lowest:
                      lowest = low
                  if high > highest:
                      highest = high
          return lowest, highest
docs: Return the active pitch range of the pianorolls of all tracks as a tuple
          (lowest, highest).
  
          Returns
          -------
          lowest : int
              The lowest active pitch among the pianorolls of all tracks.
          highest : int
              The lowest highest pitch among the pianorolls of all tracks.