Initially, writing this code can be a little dreary, but it also has a real advantage in reliability: many mysterious problems instantly disappear if you immediately reject bad data.

• 在开始时,编写这些代码可能会有一点无聊,不过它对于可靠性确实有好处:如果您拒绝了那些非法数据,许多不可思议的问题马上就会消失。