public function logout()
 {
     $this->_CI->load->model('Do_auth');
     $userSess = new Usersess();
     $session_id = get_cookie('ci_session');
     # current session
     $session_data = $this->_CI->Do_auth->getBySessionId($session_id);
     if ($session_data->remember_me == '1') {
         $this->_CI->Do_auth->removeSession($session_id);
     }
     $userSess->destroy();
 }