apscheduler error

[linna li]

I tried to use the apscheduler and used the sample code below from the
tutorial, but got the error message: Exception in thread APScheduler
(most likely raised during interpreter shutdown). What's going on
here? I really appreciate any help!

from apscheduler.scheduler import Scheduler

sched = Scheduler()
sched.start()

def some_job():
    print "Decorated job"

sched.add_interval_job(some_job,minutes=1)