@abc.abstractmethod<EOL><INDENT>def search_among_books(self, book_ids):<DEDENT>
pass<EOL>
Execute this search among the given list of books.

        :param book_ids: list of books
        :type book_ids: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``book_ids`` is ``null``

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