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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_total_multipart_upload_size(self, bucket_name, object_name, upload_id):
 """ 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. """

        return sum(
            [part.size for part in
             self._list_object_parts(bucket_name, object_name, upload_id)]
        )