// then this is "get message"
            return $this->message;
        }
    }
    private function check_login()
    {
        if (isset($_SESSION['user_id'])) {
            $this->user_id = $_SESSION['user_id'];
            $this->logged_in = true;
        } else {
            unset($this->user_id);
            $this->logged_in = false;
        }
    }
    private function check_message()
    {
        // is there a message stored in the session?
        if (isset($_SESSION['message'])) {
            // add it as an attribute and erase the stored version
            $this->message = $_SESSION['message'];
            unset($_SESSION['message']);
        } else {
            $this->message = "";
        }
    }
}
$session = new Session();
$message = $session->message();
if ($session->is_logged_in()) {
    $user = User::find_by_id($session->user_id);
}