docs: def _assert_valid_start(start_int, count_int, total_int):
      """Assert that the number of objects visible to the active subject is higher than
      the requested start position for the slice.
  
      This ensures that it's possible to create a valid slice.
  
      """
      if total_int and start_int >= total_int:
          raise d1_common.types.exceptions.InvalidRequest(
              0,
              'Requested a non-existing slice. start={} count={} total={}'.format(
                  start_int, count_int, total_int
              ),
          )