class ChildPath extends AbstractPath {

    @Override
    public Path getAncestor( int degree ) {
        CheckArg.isNonNegative(degree, "degree");
        if (degree == 0) return this;
        if (degree == 1) return parent;
        return parent.getAncestor(degree - 1);
    }

    public  ChildPath( Path parent,
                      Path.Segment child );

}