As I said, what we want to do is, we want to count the number of basic steps it takes to compute a computation as a function of input size.

我刚才提到了，我们要建立，一个根据输入大小的方法来计算,一个计算过程需要的时间,建立这个方法需要几步呢？

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The format is the same. I'm going to ask for some input, and then I am going to use that procedure to check, is this the right type of value. And I'm trying to use that to do the coercion if you like. Same thing if it works, I'm going to skip that, if it not, it's going to throw the exception.

格式是一样的，我需要一些输入,然后我要用一个过程来检查,是否是正确的值,然后你就可以做强制转换了,如果能运行，那是一样的，我打算跳过这段，如果不正确，那就会抛出一个异常。

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