public function getUser($nb_user)
    {
        $retval = null;

        $nb_user_id = nb_getMixedValue($nb_user, NABU_USER_FIELD_ID);
        if (is_numeric($nb_user_id)) {
            $nb_new_user = new CNabuUser($nb_user_id);
            if ($nb_new_user->isFetched() && $nb_new_user->validateCustomer($this)) {
                $nb_new_user->setCustomer($this);
                $retval = $nb_new_user;
            }
        }

        return $retval;
    }