@abc.abstractmethod<EOL><INDENT>def get_time_period(self):<DEDENT>
return<EOL>
Gets the ``TimePeriod`` for this recurring event.

        A ``Schedule`` with an associated ``TimePeriod`` overrides any
        start or end date set.

        :return: the time period
        :rtype: ``osid.calendaring.TimePeriod``
        :raise: ``IllegalState`` -- ``has_time_period()`` is ``false``
        :raise: ``OperationFailed`` -- unable to complete request

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