code: def pad_to_same(self):
          
          max_length = self.get_max_length()
          for track in self.tracks:
              if track.pianoroll.shape[0] < max_length:
                  track.pad(max_length - track.pianoroll.shape[0])
docs: Pad shorter pianorolls with zeros at the end along the time axis to
          make the resulting pianoroll lengths the same as the maximum pianoroll
          length among all the tracks.