@abc.abstractmethod<EOL><INDENT>def register_for_changed_commitments_for_event(self, event_id):<DEDENT>
pass<EOL>
Register for notifications of changed commitments for the given event.

        ``CommitmentReceiver.changedCommitments()`` is invoked when a
        commitment is changed.

        :param event_id: the ``Id`` of the ``Event`` to monitor
        :type event_id: ``osid.id.Id``
        :raise: ``NullArgument`` -- ``event_id is null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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