public static function ip($check, $type = 'both')
    {
        $type = strtolower($type);
        $flags = 0;
        if ($type === 'ipv4') {
            $flags = FILTER_FLAG_IPV4;
        }
        if ($type === 'ipv6') {
            $flags = FILTER_FLAG_IPV6;
        }

        return (bool)filter_var($check, FILTER_VALIDATE_IP, ['flags' => $flags]);
    }