code: def _get_total_multipart_upload_size(self, bucket_name, object_name,
                                           upload_id):
          
          return sum(
              [part.size for part in
               self._list_object_parts(bucket_name, object_name, upload_id)]
          )
docs: Get total multipart upload size.
  
          :param bucket_name: Bucket name to list parts for.
          :param object_name: Object name to list parts for.
          :param upload_id: Upload id of the previously uploaded object name.