public bool IsThreeOfAKind(IHand hand)
        {
            if (!IsValidHand(hand))
            {
                return false;
            }

            bool result = hand.Cards
                                    .GroupBy(x => x.Face)
                                    .Any(x => x.Count() == ValidIsThreeOfAKindGroupCount);

            return result;
        }

public bool IsTwoPair(IHand hand)
        {
            if (!IsValidHand(hand))
            {
                return false;
            }

            int differentCardsFacesCount = hand.Cards.GroupBy(x => x.Face).Count();

            bool result = differentCardsFacesCount == ValidIsTwoPairGroupCount;

            return result;
        }