@abc.abstractmethod<EOL><INDENT>def search_among_grade_systems(self, grade_system_ids):<DEDENT>
pass<EOL>
Execute this search among the given list of grade systems.

        :param grade_system_ids: list of grade systems
        :type grade_system_ids: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``grade_system_ids`` is ``null``

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