'Simple demo of thread groups for parallel downloads'

from urllib.request import urlretrieve
import threading

downloaders = threading.SimpleThreadGroup('downloaders')
for site in ['perl', 'python', 'jython', 'pypy']:
    url = 'http://www.{site}.org/'.format(site=site)
    filename = '{site}.html'.format(site=site)
    threading.Thread(downloaders, urlretrieve, site, (url, filename)).start()
downloaders.join()
print('Done!')