@abc.abstractmethod<EOL><INDENT>def get_book_form_for_update(self, book_id):<DEDENT>
return<EOL>
Gets the book form for updating an existing book.

        A new book form should be requested for each update transaction.

        :param book_id: the ``Id`` of the ``Book``
        :type book_id: ``osid.id.Id``
        :return: the book form
        :rtype: ``osid.commenting.BookForm``
        :raise: ``NotFound`` -- ``book_id`` is not found
        :raise: ``NullArgument`` -- ``book_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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