@abc.abstractmethod<EOL><INDENT>def set_superseded_date(self, date):<DEDENT>
pass<EOL>
Sets the superseded date.

        :param date: the new superseded date
        :type date: ``osid.calendaring.DateTime``
        :raise: ``InvalidArgument`` -- ``date`` is invalid
        :raise: ``NoAccess`` -- ``date`` cannot be modified
        :raise: ``NullArgument`` -- ``date`` is ``null``

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