tabindex without dash

function tabindex($optinid = null) {
        global $wpmltabindex;

        if (empty($wpmltabindex) || !$wpmltabindex) {
            $wpmltabindex = 1;
        }

        $wpmltabindex++;
        $tabindex = 'tabindex="' . $this -> pre . $optinid . '' . $wpmltabindex . '"';
        return $tabindex;
    }