纯python编写的有限状态机，或许我也不清除是否可以称作fsm。它以一种十分简化的方式实现了有限状态机的功能。或许称它为easyfsm更合适\n Fsm with pure python. It realizes the function of fsm in a very simplified way. Maybe it's more properly to call it 'easyfsm'