protected function checkResponse($buffer)
    {
        // Check for HARD errors. Not an unsuccessful response from command -> here = real errors
        if (preg_match('/' . self::ERROR . '(.*)\R/mu', $buffer, $error) > 0) {
            // ERROR\r\n
            $result = self::MEMCACHED_FAILURE;

        } elseif (preg_match('/' . self::ERROR_CLIENT . '(.*)\R/mu', $buffer, $error) > 0) {
            // CLIENT_ERROR\r\n
            $result = self::RESPONSE_CLIENT_ERROR;

        } elseif (preg_match('/' . self::ERROR_SERVER . '(.*)\R/mu', $buffer, $error) > 0) {
            // SERVER_ERROR\r\n
            $result = self::ERROR_SERVER;

        } else {
            $result = self::MEMCACHED_SUCCESS;
        }

        // Get and return result by response ;)
        return $this->setLastResponse($result);
    }