@abc.abstractmethod<EOL><INDENT>def add_event(self, recurring_event_id, event_id):<DEDENT>
pass<EOL>
Adds another event as part of this recurring event.

        :param recurring_event_id: a recurring event ``Id``
        :type recurring_event_id: ``osid.id.Id``
        :param event_id: an event ``Id``
        :type event_id: ``osid.id.Id``
        :raise: ``NotFound`` -- ``recurring_event_id`` or ``event_id`` is not found
        :raise: ``NullArgument`` -- ``recurring_event_id`` or ``event_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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