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

        ``CommentReceiver.changedComments()`` is invoked when a comment
        is changed.

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

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