public static function getProjectRoot()
    {
        $sep = DIRECTORY_SEPARATOR;
        $pos = strrpos(__DIR__, "${sep}vendor${sep}"); // /abc/vendor/BitRank/BitRank returns 4

        if ($pos === false) {
            return null;
        }

        $projectRoot = substr(__DIR__, 0, $pos);
        return $projectRoot;
    }