How to Restart a thread

[many_years_after]

class mythread(threading.Thread):
    def __init__(self, threadname):
        threading.Thread.__init__(self, name = threadname)

    def run(self):
        print 'i am running'
        print 'i quit run()'

thread  = mythread('1')
thread.start()
print threading.activeCount()  ## 1 , this means the thread is active
if not thread.isAlive():
    print 'i am dead,you can restart'   ### OK, this is executed. this
means the thread is no alive
    thread.start() #### " thread already started "

This program presentes that the thread quit the *run()* func and is
active but not alive.   How to understand this? It is said if the
thread quit the *run()* func , it's dead.
how to restart it ?

Thanks