Declare your collection variable to be of that type, and be sure to create an object of that same type.

将您的集合变量声明为该类型，并确保创建一个相同类型的对象。

youdao

And what it's saying semantically is, using that variable as my placeholder, have it walk through this collection, starting at the first thing, execute that code, then the next thing, execute that code, and so on.

它的语义意思就是，把这个变量应用为我的占位符，用它来遍历这个集合，从第一个元素开始，执行代码，然后下一个元素，再执行代码。

麻省理工公开课 - 计算机科学及编程导论课程节选

However, the quality of the collection has been variable.

BBC: Museum of Somerset marine insect fossil study starts