Added occupying method and eq for Piece class

chess.py

@@ -3,7 +3,7 @@ from unicodedata import lookup
 def cross(A, B):
     return tuple(a+b for a in A for b in B)
 
-ranks   = "12345678"
+ranks   = "87654321"
 files   = "abcdefgh"
 squares = cross(files, ranks)
 
@@ -29,6 +29,13 @@ class Piece:
         name = self.color.upper() + " CHESS " + self.piece.upper()
         return lookup(name)
 
+    def __eq__(self, other):
+        if other == None:
+            return  None in (self.color, self.piece)
+        if not isinstance(other, Piece):
+            return NotImplemented
+        return self.piece == other.piece and self.color == other.color
+
 class Game:
     def __init__(self):
         self.make_board()
@@ -63,7 +70,10 @@ class Game:
             self.board[sq].color = "black"
 
     def is_empty(self, sq):
-        return self.board[sq].piece == None
+        return self.board[sq] == None
+
+    def occupying(self, piece):
+        return [sq for sq in squares if self.board[sq] == piece]
 
 
 
@@ -73,5 +83,6 @@ def test():
     assert len(squares) == 8**2
     assert sum(map(len, init_positions.values())) == 8*4
     print(game)
+    print(game.occupying(Piece("white", "pawn")))
 
 test()