code: def waveform_length(X):
      ''' cumulative length of the waveform over a segment for each variable in the segmented time
      series '''
      return np.sum(np.abs(np.diff(X, axis=1)), axis=1f waveform_length(X):
      ''' cumulative length of the waveform over a segment for each variable in the segmented time
      series '''
      return np.sum(np.abs(np.diff(X, axis=1)), axis=1)
docs: cumulative length of the waveform over a segment for each variable in the segmented time
      series