问如何销毁python中的对象？

EN

class timer:
        def __init__(self, duration, function, args):
            self.duration = duration
            self.function = function
            self.args = args
        def start(self):
            self.time = time.time()
            self.validity = True    
        def check(self):
            if(int(self.time)+self.duration < time.time() ):
                self.function(self.args)
                self.validity = False
        def __del__(self):
            print("timer destroyed")