class Countdown(object):
counter = 5
def count(self):
if self.counter == 0:
reactor.stop()
else:
print (self.counter, '...')
self.counter -= 1
reactor.callLater(1, self.count)
from twisted.internet import reactor
reactor.callWhenRunning(Countdown().count)
print ('Start!')
reactor.run()
print ('Stop!')
