code: def urlize(text, trim_url_limit=None, nofollow=False):
      
      trim_url = lambda x, limit=trim_url_limit: limit is not None \
                           and (x[:limit] + (len(x) >=limit and '...'
                           or '')) or x
      words = _word_split_re.split(unicode(escape(text)))
      nofollow_attr = nofollow and ' rel="nofollow"' or ''
      for i, word in enumerate(words):
          match = _punctuation_re.match(word)
          if match:
              lead, middle, trail = match.groups()
              if middle.startswith('www.') or (
                  '@' not in middle and
                  not middle.startswith('http://') and
                  len(middle) > 0 and
                  middle[0] in _letters + _digits and (
                      middle.endswith('.org') or
                      middle.endswith('.net') or
                      middle.endswith('.com')
                  )):
                  middle = '<a href="http://%s"%s>%s</a>' % (middle,
                      nofollow_attr, trim_url(middle))
              if middle.startswith('http://') or \
                 middle.startswith('https://'):
                  middle = '<a href="%s"%s>%s</a>' % (middle,
                      nofollow_attr, trim_url(middle))
              if '@' in middle and not middle.startswith('www.') and \
                 not ':' in middle and _simple_email_re.match(middle):
                  middle = '<a href="mailto:%s">%s</a>' % (middle, middle)
              if lead + middle + trail != word:
                  words[i] = lead + middle + trail
      return u''.join(words)
docs: Converts any URLs in text into clickable links. Works on http://,
      https:// and www. links. Links can have trailing punctuation (periods,
      commas, close-parens) and leading punctuation (opening parens) and
      it'll still do the right thing.
  
      If trim_url_limit is not None, the URLs in link text will be limited
      to trim_url_limit characters.
  
      If nofollow is True, the URLs in link text will get a rel="nofollow"
      attribute.