code: def split_array_as_list(self, values):
          
          values = np.asarray(values)
          values = values[self.index.sorter]
          return np.split(values, self.index.slices[1:-1], axis=0)
docs: Group values as a list of arrays, or a jagged-array
  
          Parameters
          ----------
          values : ndarray, [keys, ...]
  
          Returns
          -------
          list of length self.groups of ndarray, [key_count, ...]