// **********************************************************************//// Copyright (c) 2003-2007 ZeroC, Inc. All rights reserved.//// This copy of Ice is licensed to you under the terms described in the// ICE_LICENSE file included in this distribution.//// **********************************************************************module Complex{//// The database key (the expression and the result). Naturally, this// is a stupid key - but this is only a test :)//struct Key{    string expression;    int result;};//// A set of classes that represents a numeric parse tree.//class Node{    int calc();};class NumberNode extends Node{    int number;};class BinaryNode extends Node{    Node left;    Node right;};class AddNode extends BinaryNode{};class MultiplyNode extends BinaryNode{};};