Added Documentation

Added Test Cases
Added Comments

core/src/api/player.rs

@@ -0,0 +1,15 @@
+use crate::api::action::Action;
+use crate::api::card::Card;
+use crate::api::game_observer::GameObserver;
+use crate::api::preferences::Preferences;
+
+pub trait Player: GameObserver {
+    /// Initialize your player from the given preferences.
+    fn init(&mut self, prefs: Box<dyn Preferences>);
+
+    /// Receive your hole cards.
+    fn hole_cards(&mut self, c1: Card, c2: Card, seat: usize);
+
+    /// Requests an Action from the player. Called when it is the Player's turn to act.
+    fn get_action(&mut self) -> Action;
+}