@abc.abstractmethod<EOL><INDENT>def get_books_by_query(self, book_query):<DEDENT>
return<EOL>
Gets a list of ``Books`` matching the given search.

        :param book_query: the book query
        :type book_query: ``osid.commenting.BookQuery``
        :return: the returned ``BookList``
        :rtype: ``osid.commenting.BookList``
        :raise: ``NullArgument`` -- ``book_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``book_query`` is not of this service

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