def get_grading_batch_manager(self):
raise Unimplemented()<EOL>
Gets the ``GradingBatchManager``.

        return: (osid.grading.batch.GradingBatchManager) - a
                ``GradingBatchManager``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_grading_batch() is false``
        *compliance: optional -- This method must be implemented if
        ``supports_grading_batch()`` is true.*