Everyone knows from calculus that if you're trying to find a function about which you know only the derivative, you can always add a constant to one person's answer without changing anything.

学过微积分的人都知道,如果你想根据已知的导数,求出其原函数,你总是可以给某人的答案,随便加一个常数,且不影响结果

耶鲁公开课 - 基础物理课程节选

Sometimes the functions -- sometimes a function can be used on multiple data types, plus, for example, we saw could add strings, or could add ints, but each one of those data types has associated with it a set of functions that are geared to handling them.

比如说，我们可以对string类型,进行add操作,也可以对int类型进行这个操作，但是这些数据类型中的每一种，都与适合于操作它们的,方法集相关联,我们想对我们创建的数据,类型做同样的事情。

麻省理工公开课 - 计算机科学及编程导论课程节选