Because I could've built that in, it says if you change the value of this thing, by the way you need to change recompute those other values in order to make this hold up.

我想要大家通过定义好的方法，来改变实例的值了,因为我可以把这个功能，内置到方法里面去,它的意思就是如果,你改变一个值。

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