Now that I've written sqrt, I can just use it anywhere I want in the code. You've got to rely on the fact that I wrote it correctly, but you can basically suppress the details of how it's used.

就是忽略细节,既然我已经编写了sqrt函数,我可以在代码的任何地方使用它，你完全可以依靠,我已经编写的这个函数。

麻省理工公开课 - 计算机科学及编程导论课程节选