diff --git a/tetris.py b/tetris.py
--- a/tetris.py
+++ b/tetris.py
@@ -74,7 +74,7 @@ def fill(board,pieces):
 				pieces[i][0]-=1
 				partialRes=fill(board,pieces)
 				if partialRes:
-					res+=[((point,v), partialRes)]
+					res.append(((point,v), partialRes))
 				remove(board,point,v)
 				pieces[i][0]+=1
 	return res