Weird things, bad things can happen and so one of the lessons too that will be repeated throughout the course is to actually rigorously error check and make sure that you're always thinking about your user being a bad guy.

各种古怪的事情就会蜂拥而至,所以在这个课程中我反复强调,要一丝不苟地检查错误,你就当你的用户是个调皮捣蛋的家伙。

哈佛公开课 - 计算机科学课程节选