public function walk($method, $firstArg = null, $secondArg = null)
    {
        if ($method === 'purge') {
            $method = 'ban';
        }

        if ($firstArg === null && $secondArg === null) {
            $this->getVarnishPool()->$method();
        } elseif ($secondArg === null) {
            $this->getVarnishPool()->$method($firstArg);
        } else {
            $this->getVarnishPool()->$method($firstArg, $secondArg);
        }

        return $this;
    }