docs: def get_mean_per_split(self):
          """Get the mean elapsed time per split of each stopwatch (excluding the current split).
  
          Returns
          -------
          mean_elapsed_time_per_split : List[datetime.timedelta]
          """
          return [div_timedelta(sum(stopwatch.split_elapsed_time, datetime.timedelta()),
                                len(stopwatch.split_elapsed_time))
                  if stopwatch.split_elapsed_time else datetime.timedelta()
                  for stopwatch in self]