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

        ``ObjectiveReceiver.changedObjectives()`` is invoked when an
        objective is changed.

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

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