private static function getFlippedTimezones()
    {
        if (null === static::$timezones) {
            static::$timezones = [];

            foreach (\DateTimeZone::listIdentifiers() as $timezone) {
                $parts = explode('/', $timezone);

                if (\count($parts) > 2) {
                    $region = $parts[0];
                } elseif (\count($parts) > 1) {
                    $region = $parts[0];
                } else {
                    $region = 'Other';
                }

                static::$timezones[$region][str_replace('_', ' ', $timezone)] = $timezone;
            }
        }

        return static::$timezones;
    }