Ctrl-C многопоточной программы на Python

#!/usr/bin/python
# -*- coding: utf-8 -*-

import threading
import Queue

import time
def worker():
    while True:
        item = q.get()
        time.sleep(60)
        print item
        q.task_done()

num_worker_threads = 20
q = Queue.Queue()
for i in range(num_worker_threads):
     t = threading.Thread(target=worker)
     t.daemon = True
     t.start()

def source():
  return range(100)

for item in source():
    q.put(item)

q.join()       # block until all tasks are done