code: def saccadic_momentum_effect(durations, forward_angle,
                               summary_stat=nanmean):
      
      durations_per_da = np.nan * np.ones((len(e_angle) - 1,))
      for i, (bo, b1) in enumerate(zip(e_angle[:-1], e_angle[1:])):
          idx = (
              bo <= forward_angle) & (
              forward_angle < b1) & (
              ~np.isnan(durations))
          durations_per_da[i] = summary_stat(durations[idx])
      return durations_per_da
docs: Computes the mean fixation duration at forward angles.