static ScorableHand?StraightPattern(Hand h)
{
var high = RankValue(h);
var lowHypothetical = high - 4;
var lowStraightRanking = new [] { Ace, 5, 4, 3, 2 };
var typicalRanking = Enumerable.Range(lowHypothetical, 5).Reverse();
return(h switch {
Hand hl when lowStraightRanking.SequenceEqual(Ranking(hl)) =>
ScorableHand.NewEntireHand(hl.Select(c => c.Rank == Ace ? new (1, c.Suit): c)),
Hand hx when typicalRanking.SequenceEqual(Ranking(hx)) =>
ScorableHand.NewEntireHand(hx),
_ => null
});
static ScorableHand?FlushPattern(Hand h) =>
IsFlush(h)
? ScorableHand.NewEntireHand(h)
: null;