docs: def expected_part_size(self, part_number):
          """Get expected part size for a particular part number."""
          last_part = self.multipart.last_part_number
  
          if part_number == last_part:
              return self.multipart.last_part_size
          elif part_number >= 0 and part_number < last_part:
              return self.multipart.chunk_size
          else:
              raise MultipartInvalidPartNumber()