As the in function runs, it calls several functions in the class passed to it.

in函数运行时，会调用传递给它的类中的几个函数。

youdao

A member function with private visibility can only be invoked by other member functions in the class in which it is defined, but not in the subclasses.

具有私有可视性的成员函数只能由与该成员函数在同一个类中定义的其它成员函数调用，而在子类中的成员函数不能调用该成员函数。

youdao

These functions are implemented in the Publisher class.

这些函数是在 Publisher 类中实现的。

youdao

This is boring. In fact, you can do some nice things to prove what is the class of functions you can compute with straight-line programs, and what you'd see if you did that is, it's not particularly interesting.

这很无聊，实际上，你可以通过做一些很有趣的事情,来证明你可以通过直线程序,来做很多功能，但是你也看到我们之前讲过的了，这不太有趣。

麻省理工公开课 - 计算机科学及编程导论课程节选