@abc.abstractmethod<EOL><INDENT>def supersedes_by_date(self):<DEDENT>
return<EOL>
Tests if the superseding event replaces an event within a recurring series offered at a specific date/time.

        If ``supersedes_by_date()`` is true, then
        ``supersedes_by_position()`` must be false.

        :return: ``true`` if an event is superseded by date, ``false`` otherwise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

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