Что делает if name = = "main": делать?

Что делает if __name__ == "__main__":?

# Threading example

import time, thread



def myfunction(string, sleeptime, lock, *args):

    while True:

        lock.acquire()

        time.sleep(sleeptime)

        lock.release()

        time.sleep(sleeptime)



if __name__ == "__main__":

    lock = thread.allocate_lock()

    thread.start_new_thread(myfunction, ("Thread #: 1", 2, lock))

    thread.start_new_thread(myfunction, ("Thread #: 2", 2, lock))