@abc.abstractmethod<EOL><INDENT>def supersedes_by_position(self):<DEDENT>
return<EOL>
Tests if the superseding event replaces an event within a recurring series identified by its denormalized
        position in the series.

        A negative number counts from the end of the series. If
        ``supersedes_by_position()`` is ``true,`` then
        ``supersedes_by_date()`` must be ``false``.

        :return: ``true`` if an event is superseded by position, ``false`` otherwise
        :rtype: ``boolean``

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