@abc.abstractmethod<EOL><INDENT>def is_superseding_event(self):<DEDENT>
return<EOL>
Tests if this event is a superseding event.

        If true, ``is_implicit()`` must also be true.

        :return: ``true`` if this event is superseding event, ``false`` otherwise
        :rtype: ``boolean``

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