code: def validate(self, request, response):
          
          element = self.search_response(request)
          if element is not None:
              element.cached_response.options = response.options
              element.freshness = True
              element.max_age = response.max_age
              element.creation_time = time.time()
              element.uri = request.proxy_uri
docs: refreshes a resource when a validation response is received
  
          :param request:
          :param response:
          :return: