@abc.abstractmethod<EOL><INDENT>def get_superseding_event_ids(self):<DEDENT>
return<EOL>
Gets the superseding event ``Ids``.

        A superseding event is one that replaces another in a series.

        :return: list of superseding event ``Ids``
        :rtype: ``osid.id.IdList``

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