to do sqrt, or square root-- no, I'm going to square root use sqrt, that's the name I'm using here-- square root a hundred different places in some piece of code. Without function, I'd have to copy that piece of code everywhere.

让我做一下准备,想象一下我要调用sqrt或者-,不，我会调用sqrt函数,这是我在这里用的名字，我得把这段代码到处复制。

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