public function isWorking()
    {
        $settings = self::getGeoIpServerVars();

        $available = array_key_exists($settings[self::CONTINENT_CODE_KEY], $_SERVER)
            || array_key_exists($settings[self::COUNTRY_CODE_KEY], $_SERVER)
            || array_key_exists($settings[self::REGION_CODE_KEY], $_SERVER)
            || array_key_exists($settings[self::CITY_NAME_KEY], $_SERVER);

        if (!$available) {
            return Piwik::translate("UserCountry_CannotFindGeoIPServerVar", $settings[self::COUNTRY_CODE_KEY] . ' $_SERVER');
        }

        return true;
    }