@abc.abstractmethod<EOL><INDENT>def register_for_changed_comment(self, comment_id):<DEDENT>
pass<EOL>
Registers for notification of an updated comment.

        ``CommentReceiver.changedComments()`` is invoked when the
        specified comment is changed.

        :param comment_id: the ``Id`` of the ``Comment`` to monitor
        :type comment_id: ``osid.id.Id``
        :raise: ``NotFound`` -- a comment was not found identified by the given ``Id``
        :raise: ``NullArgument`` -- ``comment_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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