public static function convertRegionCodeToIso($countryCode, $fipsRegionCode, $returnOriginalIfNotFound = false)
    {
        static $mapping;
        if(empty($mapping)) {
            $mapping = include __DIR__ . '/../data/regionMapping.php';
        }
        $countryCode = strtoupper($countryCode);
        if (empty($countryCode) || in_array($countryCode, ['EU', 'AP', 'A1', 'A2'])) {
            return ['', ''];
        }
        if (in_array($countryCode, ['US', 'CA'])) { // US and CA always haven been iso codes
            return [$countryCode, $fipsRegionCode];
        }
        if ($countryCode == 'TI') {
            $countryCode = 'CN';
            $fipsRegionCode = '14';
        }
        $isoRegionCode = $returnOriginalIfNotFound ? $fipsRegionCode : '';
        if (!empty($fipsRegionCode) && !empty($mapping[$countryCode][$fipsRegionCode])) {
            $isoRegionCode = $mapping[$countryCode][$fipsRegionCode];
        }
        return [$countryCode, $isoRegionCode];
    }