public static function check_browser_version($brand, $version = null) {
        switch ($brand) {

            case 'MSIE':
                // Internet Explorer.
                return self::check_ie_version($version);

            case 'Edge':
                // Microsoft Edge.
                return self::check_edge_version($version);

            case 'Firefox':
                // Mozilla Firefox browsers.
                return self::check_firefox_version($version);

            case 'Chrome':
                return self::check_chrome_version($version);

            case 'Opera':
                // Opera.
                return self::check_opera_version($version);

            case 'Safari':
                // Desktop version of Apple Safari browser - no mobile or touch devices.
                return self::check_safari_version($version);

            case 'Safari iOS':
                // Safari on iPhone, iPad and iPod touch.
                return self::check_safari_ios_version($version);

            case 'WebKit':
                // WebKit based browser - everything derived from it (Safari, Chrome, iOS, Android and other mobiles).
                return self::check_webkit_version($version);

            case 'Gecko':
                // Gecko based browsers.
                return self::check_gecko_version($version);

            case 'WebKit Android':
                // WebKit browser on Android.
                return self::check_webkit_android_version($version);

            case 'Camino':
                // OSX browser using Gecke engine.
                return self::check_camino_version($version);
        }
        // Who knows?! doesn't pass anyway.
        return false;
    }