Python 是否有方法拒绝计划的计时器事件？

想想这个。我想拒绝执行计时器事件：

import threading


def say_hello():
    print 'hello'

threading.Timer(10, say_hello, ()).start()
# now for some reason my plans have changed
# is there a way to erase that Timer and deny execution of say_hello?

t = threading.Timer(10, say_hello, ())
t.start()  # start timer
t.cancel()  # stop it