code: def summarize(urls):
      
      import time
      from summary import Summary
  
  
      fails = 0
      err = lambda e: e.__class__.__name__
  
      summaries = []
      start = time.time()
      for url in urls:
          try:
              print "-> %s" % url
              summary = Summary(url)
              summary.extract()
          except KeyboardInterrupt:
              break
          except Exception, e:
              fails += 1
              summary = {
                  'titles': ["[%s]" % err(e)],
                  'urls': [url],
                  'descriptions': [str(e)],
                  'source': url,
                  }
              print "[%s] (%s): %s" % (err(e), e, url)
          summaries.append(summary)
          end = time.time()
  
      result = fails and "Fails: %s out of %s." % (fails, len(summaries)) \
          or "Success: %s." % len(summaries)
      print result
  
      duration = end - start
      speed = "%.2f" % (duration/len(summaries))
  
      return summaries, result, speed
docs: Calls extract for each of the URLs,
      Returns the list of Extracted instances as summaries, 
      the result of the process, and the speed.