在Python中停止计时器后，计时器无法重新启动

这是更正的版本：

from __future__ import print_functionfrom threading import Timerdef hello():    print("Hello World!")class RepeatingTimer(object):    def __init__(self, interval, f, *args, **kwargs):        self.interval = interval        self.f = f        self.args = args        self.kwargs = kwargs        self.timer = None    def callback(self):        self.f(*self.args, **self.kwargs)        self.start()    def cancel(self):        self.timer.cancel()    def start(self):        self.timer = Timer(self.interval, self.callback)        self.timer.start()t = RepeatingTimer(3, hello)t.start()

示例运行：

$ python -i foo.py>>> Hello World!>>> Hello World!>>> t.cancel()