@abc.abstractmethod<EOL><INDENT>def get_grading_batch_proxy_manager(self):<DEDENT>
return<EOL>
Gets the ``GradingBatchProxyManager``.

        :return: a ``GradingBatchProxyManager``
        :rtype: ``osid.grading.batch.GradingBatchProxyManager``
        :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.*