if( !(numberToNode.get(id) instanceof BaseNode) ) System.err.println("Lookup class failure for "+id+" "+numberToNode.get(id).getClass().getName());
    public Node lookup(String id) {      if( !(numberToNode.get(id) instanceof BaseNode) )        System.err.println("Lookup class failure for "+id+" "+numberToNode.get(id).getClass().getName()); //zzz      return (Node) numberToNode.get(id);    }