private function getLogins($players, $allowEmpty = false)
    {
        if (is_array($players)) {
            $logins = array();
            foreach ($players as $player) {
                $login = $this->getLogin($player);
                if ($login === false) {
                    return false;
                }
                $logins[] = $login;
            }

            return implode(',', $logins);
        }
        return $this->getLogin($players, $allowEmpty);
    }