code: def check(self, url_data):
          
          self.timer.check_w3_time()
          session = url_data.session
          try:
              body = {'uri': url_data.url, 'output': 'soap12'}
              response = session.post('http://validator.w3.org/check', data=body)
              response.raise_for_status()
              if response.headers.get('x-w3c-validator-status', 'Invalid') == 'Valid':
                  url_data.add_info(u"W3C Validator: %s" % _("valid HTML syntax"))
                  return
              check_w3_errors(url_data, response.text, "W3C HTML")
          except requests.exceptions.RequestException:
              pass # ignore service failures
          except Exception as msg:
              log.warn(LOG_PLUGIN, _("HTML syntax check plugin error: %(msg)s ") % {"msg": msg})
docs: Check HTML syntax of given URL.