docs: def summarize_url(url, num_sentences=4, fmt='default'):
      '''returns: tuple containing
         * single-line summary candidate 
         * key points
         in the format specified.
      '''
  
      title, meta, full_text = goose_extractor(url)
  
      if not full_text:
          raise ArticleExtractionFail("Couldn't extract: {}".format(url))
  
      its = _intertext_score(full_text)
      tss = _title_similarity_score(full_text,title)
  
      if _eval_meta_as_summary(meta):
          summ = meta
          if tss[0][2].lower() in summ.lower():
              its, tss = _remove_title_from_tuples(its, tss)
          elif summ.lower() in tss[0][2].lower():
              summ = tss[0][2]
              its, tss = _remove_title_from_tuples(its, tss)
      else:
          summ = tss[0][2]
          its, tss = _remove_title_from_tuples(its, tss)
  
      scores = [score[2] for score in _aggregrate_scores(its, tss, num_sentences)]
      formatted = Formatter(scores, fmt).frmt()
      return summ, formatted