目录__getattr____getattribute____getattr__ 当访问实例对象的某个不存在的属性时，毫无疑问会报错，会抛出 AttributeError。
I am trying to prevent my application calling the same method twice in the event of a double-cli开发者_如何学Pythonck, or if the user presses different buttons quickly, almost at the same time.
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