@abc.abstractmethod<EOL><INDENT>def deleted_gradebook_columns(self, notification_id, gradebook_column_ids):<DEDENT>
pass<EOL>
The callback for notification of deleted gradebook columns.

        :param notification_id: the notification ``Id``
        :type notification_id: ``osid.id.Id``
        :param gradebook_column_ids: the ``Ids`` of the deleted ``GradebookColumns``
        :type gradebook_column_ids: ``osid.id.IdList``


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