from threading import Timer
class MyTimer:
 def __init__(self):
 self._timer= None
 self._tm = None
 self._fn = None
 def _do_func(self):
 if self._fn:
  self._fn()
  self._do_start()
 def _do_start(self):
 self._timer = Timer(self._tm, self._do_func)
 self._timer.start()
 def start(self, tm, fn):
 self._fn = fn
 self._tm = tm
 self._do_start()
 def stop(self):
 try:
  self._timer.cancel()
 except:
  pass
def hello():
 from datetime import datetime
 print("hello world!", datetime.now())
if __name__ == '__main__':
 mt = MyTimer()
 mt.start(2, hello)
 for i in range(10):
 import time
 time.sleep(1)
 mt.stop()