card#️⃣ implement hashing for ranks, suits, playing cards

src/card/hash.rs

@@ -1,6 +1,26 @@
-use crate::card::Card;
+use crate::card::{Card, PlayingCard, Rank, Suit};
 use std::hash::{Hash, Hasher};
 
+impl Hash for Rank {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        (*self as i64).hash(state);
+    }
+}
+
+impl Hash for Suit {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        (*self as i64).hash(state);
+    }
+}
+
+impl Hash for PlayingCard {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        // NOTE: We're using the i64 conversion of card for the hash since that
+        // should generate unique numbers per card.
+        i64::from(*self).hash(state);
+    }
+}
+
 impl Hash for Card {
     fn hash<H: Hasher>(&self, state: &mut H) {
         // NOTE: We're using the i64 conversion of card for the hash since that