code: def _check_by_re(self, url_data, content):
          
          for link_re in self._link_res:
              for u in link_re.finditer(content):
                  self._save_url(url_data, content, u.group(1), u.start(1))
docs: Finds urls by re.
  
          :param url_data: object for url storing
          :param content: file content