List of users(可选，一个组可以为空)。

List of users (optional, a group may be empty).

youdao

该组成员数也要控制数量，但是不要让这个组是空的。

The members of this group should also be limited, but typically not empty.

youdao

XML文档可以使用内部不包含任何内容的空标记，这些标记可以表示为单个标记，而不是一组开始和结束标记。

An XML document can have some empty tags that do not have anything inside and can be expressed as a single tag instead of as a set of beginning and end tags.

youdao

I'm going to give a name to that. And what you see there is I'm going to call divisors initially an empty tuple, something has nothing in it. Right here. And then I'm going to run through the same loop as before, going through this set of things, doing the check.

你们可以看到这里,我初始化一个空的元组,名为divisiors，这里，然后我会去运行,跟以前一样的循环，遍历这个集合内的东西,然后做检查，现在我要做的是，每次我找到了一个除数我要把它收集起来。

麻省理工公开课 - 计算机科学及编程导论课程节选