@abc.abstractmethod<EOL><INDENT>def get_grade_systems_by_query(self, grade_system_query):<DEDENT>
return<EOL>
Gets a list of ``GradeSystem`` objects matching the given grade system query.

        :param grade_system_query: the grade system query
        :type grade_system_query: ``osid.grading.GradeSystemQuery``
        :return: the returned ``GradeSystemList``
        :rtype: ``osid.grading.GradeSystemList``
        :raise: ``NullArgument`` -- ``grade_system_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``grade_system_query`` is not of this service

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