@abc.abstractmethod<EOL><INDENT>def is_effective_by_cyclic_event(self):<DEDENT>
return<EOL>
Tests if the effectiveness of the enabler is governed by a ``CyclicEvent``.

        If a cyclic event exists, it is evaluated by the accompanying
        cyclic time period. If ``is_effective_by_cyclic_event()`` is
        ``true,`` ``is_effective_by_schedule()`` and
        ``is_effective_by_event()`` must be ``false``.

        :return: ``true`` if the enabler is governed by a cyclic event, ``false`` otherwise
        :rtype: ``boolean``


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