code: def _checkAuth(self, message, server_url):
          
          logging.info('Using OpenID check_authentication')
          request = self._createCheckAuthRequest(message)
          if request is None:
              return False
          try:
              response = self._makeKVPost(request, server_url)
          except (fetchers.HTTPFetchingError, ServerError) as e:
              e0 = e.args[0]
              logging.exception('check_authentication failed: %s' % e0)
              return False
          else:
              return self._processCheckAuthResponse(response, server_url)
docs: Make a check_authentication request to verify this message.
  
          @returns: True if the request is valid.
          @rtype: bool