@abc.abstractmethod<EOL><INDENT>def get_grading_agent_id(self):<DEDENT>
return<EOL>
Gets the ``Id`` of the ``Agent`` that created this entry.

        :return: the ``Id`` of the ``Agent``
        :rtype: ``osid.id.Id``
        :raise: ``IllegalState`` -- ``is_graded()`` is ``false`` or ``is_derived()`` is ``true``

        *compliance: mandatory -- This method must be implemented.*