code: public function afterGetType(Config $config, $result)
      {
          if (!($config instanceof \Fastly\Cdn\Model\Config)) {
              if ($result == \Fastly\Cdn\Model\Config::FASTLY) {
                  return Config::VARNISH;
              }
          }
          return $result;
      }
docs: Return cache type "Varnish" if Fastly is configured.
  
  @param Config $config
  @param string $result
  
  @return int