let string_of_rank (rank: rank) : string =
match rank with
| One -> "One"
| Two -> "Two"
| Three -> "Three"
| Four -> "Four"
| Five -> "Five"
| Six -> "Six"
| Seven -> "Seven"
| Eight -> "Eight"
| Nine -> "Nine"
| Ten -> "Ten"
| Jack -> "Jack"
| Queen -> "Queen"
| King -> "King"
| Ace -> "Ace"