call_uselessmethod 要求首先有一个实例 Class2 。但是，这样做：

call_uselessmethod requires that there first be an instance of Class2 before you use it. However, by doing this:

k = Class2

您不会将 k 分配给 Class2 的实例， Class2 本身。

you are not assigning k to an instance of Class2 but rather Class2 itself.

创建 Class2 ，在类名后添加（）：

To create an instance of Class2, add () after the class name:

k = Class2()
k.call_uselessmethod()

现在，您的代码将工作，因为 k 指向 Class2 的实例。

Now, your code will work because k points to an instance of Class2 like it should.