@abc.abstractmethod<EOL><INDENT>def changed_compositions(self, notification_id, composition_ids):<DEDENT>
pass<EOL>
The callback for notification of updated compositions.

        :param notification_id: the notification ``Id``
        :type notification_id: ``osid.id.Id``
        :param composition_ids: the ``Ids`` of the updated ``Compositions``
        :type composition_ids: ``osid.id.IdList``


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