Session::set PHP Method

    public static function set($key, $value)
    {
        $_SESSION[$key] = $value;
    }

 /**
  * Set page width
  *
  * @param  string  $width
  */
 public function width($width)
 {
     $this->session->set('page_width', $width == 'wide' ? 'liquid' : 'fixed');
     if (request::is_ajax()) {
         return;
     }
     url::back();
 }