private function _get_session($attr){
    //die(\bbn\x::hdump(self::$sn, $this->session->has(self::$sn), $attr, $this->session->get(self::$sn)));
    if ( $this->session->has(self::$sn) ){
      return $attr ?
        $this->session->get(self::$sn, $attr) :
        $this->session->get(self::$sn);
    }
  }