[Python] write demo time, pycharm editor always prompt "method XX may be static"

Figure:

 

I have obsessive-compulsive disorder, looked uncomfortable, then the next Baidu know why:

Said that this method may be a static method, as we stated in the class this method does not use class variables, so the editor reminds us this is a static method, it can safely be declared as static type

After modification, will not appear this suggests