import sched, time, threading

print('Adding')
s = sched.scheduler(time.time, time.sleep)
s.enter(1.5, 0, print, ('start event',))
t = threading.Thread(target=s.run)
t.start()
for i in range(3):
    print('adding', i)
    s.enter(i, 0, print, ('event', i))
    print('added', i)
t.join()

print('Canceling')
s = sched.scheduler(time.time, time.sleep)
events = [s.enter(i + 1, 0, print, ('event', i)) for i in range(3)]
t = threading.Thread(target=s.run)
t.start()
for e in events:
    s.cancel(e)
t.join()