class MoneySource implements Permission {

    public String value() {
        if (!wallet && !card) {
            throw new IllegalArgumentException("money-source expected");
        }
        String params;
        if (wallet && card)
            params = WALLET + "\",\"" + CARD;
        else  {
            params = card ? CARD : WALLET;
        }
        return "money-source(\"" + params + "\")";
    }

    public  MoneySource(boolean wallet, boolean card);

}