@abc.abstractmethod<EOL><INDENT>def register_for_changed_events(self):<DEDENT>
pass<EOL>
Registers for notification of updated events.

        ``EventReceiver.changedEvents()`` is invoked when an event is
        changed.

        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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