@abc.abstractmethod<EOL><INDENT>def order_repository_results(self, repository_search_order):<DEDENT>
pass<EOL>
Specify an ordering to the search results.

        :param repository_search_order: repository search order
        :type repository_search_order: ``osid.repository.RepositorySearchOrder``
        :raise: ``NullArgument`` -- ``repository_search_order`` is ``null``
        :raise: ``Unsupported`` -- ``repository_search_order`` is not of this service

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