public void visit(IAsNode value)
{
string s = value.GetType().Name + ".";
//prepare_node(value.left, s + "left");
//prepare_node(value.right, s + "right");
prepare_node(value.type, s + "type");
}
public void visit(IAsNode value)
{
throw new System.NotSupportedException(value.GetType().ToString());
}