//private void internWalk(int level, Visitable v)
//{
//v.pre(level, this);
//for (AbstractNode c = child; c != null; c = c.mysib)
//{
//c.internWalk(level + 1, v);
//}
//v.post(level, this);
//}
/// <summary>
/// Reflective visitor pattern </summary>
public void Visit(AbstractNode v)
{
Console.WriteLine("Visiting ( " + v.dump() + " )");
}
