private boolean suitMoveIsValid(Card.Suit from, Card.Suit to) {
        switch (to) {
            case HEARTS:
                return from != Card.Suit.DIAMONDS;
            case DIAMONDS:
                return from != Card.Suit.HEARTS;
            case CLUBS:
                return from != Card.Suit.SPADES;
            case SPADES:
                return from != Card.Suit.CLUBS;
            default:
                return false;
        }
    }