public function output($args = null) {
        // calculate diff
        $diff = $this->end->diff($this->begin);

        // decide stuff
        $msg = [];
        if($diff->d > 0) $msg[] = $this->plural($diff->d, 'd');
        if($diff->h > 0) $msg[] = $this->plural($diff->h, 'h');
        if($diff->i > 0) $msg[] = $this->plural($diff->i, 'i');
        $msg[] = $this->plural($diff->s);

        // return stuff
        return $this->str_lreplace(',', ' ' . __d('Unimatrix/cake', 'and'), implode(', ', $msg));
    }