code: def handle_starttag(self, tag, attrs):
          
          if not tag == 'a':
              return
  
          for attr in attrs:
              if attr[0] == 'href':
                  # Links look like: /pub/firefox/nightly/2015/
                  # We have to trim the fragment down to the last item. Also to ensure we
                  # always get it, we remove a possible final slash first
                  url = urllib.unquote(attr[1])
                  self.active_url = url.rstrip('/').split('/')[-1]
  
                  return
docs: Callback for when a tag gets opened.