@abc.abstractmethod<EOL><INDENT>def order_by_cumulative_rating(self, book_id, style):<DEDENT>
pass<EOL>
Orders by the cumulative rating in a given ``Book``.

        :param book_id: a book ``Id``
        :type book_id: ``osid.id.Id``
        :param style: search order style
        :type style: ``osid.SearchOrderStyle``
        :raise: ``NullArgument`` -- ``book_id`` or ``style`` is ``null``

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