I'm gonna keep as part of each stock, it's history of prices, which we can initialize, well, I've initialized it as empty, but that's probably the wrong thing, right?

我会把股票的历史价格，作为每只股票的一部分，我们可以先对它的历史价格进行赋值，好了，我先给它赋了空值，但是这样做可能不对，是吗？

麻省理工公开课 - 计算机科学及编程导论课程节选

Possibly an empty set of constraints.

约束条件得出的也可能是空值。

麻省理工公开课 - 计算机科学及编程导论课程节选