diff --git a/go.py b/go.py
index 2b87ee2..53de8b8 100644
--- a/go.py
+++ b/go.py
@@ -41,10 +41,10 @@ def remove(self):
     @property
     def neighbors(self):
         """Return a list of neighboring points."""
-        neighboring = [(self.point[0]-1, self.point[1]),
-                       (self.point[0]+1, self.point[1]),
-                       (self.point[0], self.point[1]-1),
-                       (self.point[0], self.point[1]+1)]
+        neighboring = [(self.point[0] - 1, self.point[1]),
+                       (self.point[0] + 1, self.point[1]),
+                       (self.point[0], self.point[1] - 1),
+                       (self.point[0], self.point[1] + 1)]
         for point in neighboring:
             if not 0 < point[0] < 20 or not 0 < point[1] < 20:
                 neighboring.remove(point)
diff --git a/goban.py b/goban.py
index ef6fc02..85f7357 100755
--- a/goban.py
+++ b/goban.py
@@ -25,7 +25,7 @@ class Stone(go.Stone):
     def __init__(self, board, point, color):
         """Create, initialize and draw a stone."""
         super(Stone, self).__init__(board, point, color)
-        self.coords = (5+self.point[0]*40, 5+self.point[1]*40)
+        self.coords = (5 + self.point[0] * 40, 5 + self.point[1] * 40)
         self.draw()
 
     def draw(self):
@@ -35,7 +35,7 @@ def draw(self):
 
     def remove(self):
         """Remove the stone from board."""
-        blit_coords = (self.coords[0]-20, self.coords[1]-20)
+        blit_coords = (self.coords[0] - 20, self.coords[1] - 20)
         area_rect = pygame.Rect(blit_coords, (40, 40))
         screen.blit(background, blit_coords, area_rect)
         pygame.display.update()
@@ -65,15 +65,30 @@ def draw(self):
         self.outline.inflate_ip(20, 20)
         for i in range(18):
             for j in range(18):
-                rect = pygame.Rect(45+(40*i), 45+(40*j), 40, 40)
+                rect = pygame.Rect(45 + (40 * i), 45 + (40 * j), 40, 40)
                 pygame.draw.rect(background, BLACK, rect, 1)
         for i in range(3):
             for j in range(3):
-                coords = (165+(240*i), 165+(240*j))
+                coords = (165 + (240 * i), 165 + (240 * j))
                 pygame.draw.circle(background, BLACK, coords, 5, 0)
         screen.blit(background, (0,0))
         pygame.display.update()
 
+    def update_liberties(self, added_stone=None):
+        """Updates the liberties of the entire board, group by group.
+        
+        Usually a stone is added each turn. To allow killing by 'suicide',
+        all the 'old' groups should be updated before the newly added one.
+        
+        """
+        for group in self.groups:
+            if added_stone:
+                if group == added_stone.group:
+                    continue
+            group.update_liberties()
+        if added_stone:
+            added_stone.group.update_liberties()
+
 
 def main():
     while True:
@@ -83,15 +98,14 @@ def main():
                 exit()
             if event.type == pygame.MOUSEBUTTONDOWN:
                 if event.button == 1 and board.outline.collidepoint(event.pos):
-                    x = int(round(((event.pos[0]-5) / 40.0), 0))
-                    y = int(round(((event.pos[1]-5) / 40.0), 0))
+                    x = int(round(((event.pos[0] - 5) / 40.0), 0))
+                    y = int(round(((event.pos[1] - 5 ) / 40.0), 0))
                     stone = board.search(point=(x, y))
                     if stone:
                         stone.remove()
                     else:
-                        stone = Stone(board, (x, y), board.turn())
-        for group in board.groups:
-            group.update_liberties()
+                        added_stone = Stone(board, (x, y), board.turn())
+        board.update_liberties(locals().get('added_stone', ''))
 
 
 if __name__ == '__main__':