diff --git a/pyalapin/engine/engine.py b/pyalapin/engine/engine.py
index ffb626e..c048c64 100644
--- a/pyalapin/engine/engine.py
+++ b/pyalapin/engine/engine.py
@@ -430,8 +430,12 @@ def deepcopy(self, light=True):
         else:
             copied_material = self.deep_copy_material()
 
-        assert len(copied_material["black"]["alive"]["king"]) > 0, "Black king is dead ?"
-        assert len(copied_material["white"]["alive"]["king"]) > 0, "White king is dead ?"
+        assert (
+            len(copied_material["black"]["alive"]["king"]) > 0
+        ), "Black king is dead ?"
+        assert (
+            len(copied_material["white"]["alive"]["king"]) > 0
+        ), "White king is dead ?"
         copied_object.white_king = copied_material["white"]["alive"]["king"][0]
         copied_object.black_king = copied_material["black"]["alive"]["king"][0]
         copied_object.all_material = copied_material
diff --git a/pyalapin/interface/interface.py b/pyalapin/interface/interface.py
index 5971d02..5e1d0e7 100644
--- a/pyalapin/interface/interface.py
+++ b/pyalapin/interface/interface.py
@@ -315,11 +315,19 @@ def click_cell(self, event):
                     if game_is_on[0]:
                         self.update()
                         (
-                            self.cells[ai_move.start.x][ai_move.start.y].background_normal,
-                            self.cells[ai_move.start.x][ai_move.start.y].background_down,
+                            self.cells[ai_move.start.x][
+                                ai_move.start.y
+                            ].background_normal,
+                            self.cells[ai_move.start.x][
+                                ai_move.start.y
+                            ].background_down,
                         ) = (
-                            self.cells[ai_move.start.x][ai_move.start.y].background_down,
-                            self.cells[ai_move.start.x][ai_move.start.y].background_normal,
+                            self.cells[ai_move.start.x][
+                                ai_move.start.y
+                            ].background_down,
+                            self.cells[ai_move.start.x][
+                                ai_move.start.y
+                            ].background_normal,
                         )
                         (
                             self.cells[ai_move.end.x][ai_move.end.y].background_normal,