code: def _insertions(self, result, dimension, dimension_index):
          
  
          def iter_insertions():
              for anchor_idx, addend_idxs in dimension.hs_indices:
                  insertion_idx = (
                      -1
                      if anchor_idx == "top"
                      else result.shape[dimension_index] - 1
                      if anchor_idx == "bottom"
                      else anchor_idx
                  )
                  addend_fancy_idx = tuple(
                      [slice(None) for _ in range(dimension_index)]
                      + [np.array(addend_idxs)]
                  )
                  yield (
                      insertion_idx,
                      np.sum(result[addend_fancy_idx], axis=dimension_index),
                  )
  
          return [insertion for insertion in iter_insertions()]
docs: Return list of (idx, sum) pairs representing subtotals.
  
          *idx* is the int offset at which to insert the ndarray subtotal
          in *sum*.