public function getStream()
    {
        $fp = @fopen($this->getPath(), 'rb');

        if ($fp === false) {
            $msg = "Cannot retrieve QTI File Stream from '" . $this->getPath() . "'.";
            throw new RuntimeException($msg);
        }

        $len = current(unpack('S', fread($fp, 2)));
        fseek($fp, $len, SEEK_CUR);

        $len = current(unpack('S', fread($fp, 2)));
        fseek($fp, $len, SEEK_CUR);

        return $fp;
    }