As you can see, we have a button that calls a function.

你可以看到，我们有一个按钮，调用一个函数。

youdao

We actually don't have to declare a class that subclasses Button with Subject.

我们实际上不用声明一个继承subject的Button的子类。

youdao

We actually don't have to declare a class that subclasses Button with Subject.

我们实际上不用声明一个继承subject的Button的子类。

youdao