@abc.abstractmethod<EOL><INDENT>def set_grade_system(self, grade_system_id):<DEDENT>
pass<EOL>
Sets the grading system.

        :param grade_system_id: the grade system
        :type grade_system_id: ``osid.id.Id``
        :raise: ``InvalidArgument`` -- ``grade_system_id`` is invalid
        :raise: ``NoAccess`` -- ``Metadata.isReadOnly()`` is ``true``

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