php - Call to undefined method Template::append_css() -

i trying append_css using code below. on older projects below code work. reference using codeigniter , template sparks

    public function __construct() {     parent::__construct();     $this->load->library('template');     $this->template             ->append_css('/public/css/app.css');   }     public function index(){             $this->template->build('welcome_message.php');     } } 

i following error

fatal error: call undefined method template::append_css() in /users/afont/quals/codeigniter-test/application/controllers/welcome.php on line 9 

first, in autoload.php, may want autoload spark:

$autoload['sparks'] = array('template/1.9.0');

second, looking through code, seems there no append_css function. in pyrocms, library appears have function, not spark default.