程序测试可以用来显示错误的存在，但永远不能显示它们的缺失！
Program testing can be used to show the presence of bugs, but never to show their absence!
The first man who， having fenced in a piece of land， said 'This is mine，' and found people naïve enough to believe him， that man was the true founder of civil society.
你必须忠于自己和你的艺术。