def popular_urls():
 with open(POPULAR_URLS) as f:
  urls = [('http://' + u.strip()) for u in f.readlines()]
  return urls

def popular_urls ( ) : with open ( POPULAR_URLS ) as f : urls = [ ( 'http://' + u . strip ( ) ) for u in f . readlines ( ) ] return urls
returns a list of pre-extracted popular source urls .