anchor.diff:  
     void rotateAll() {
       for (var i = 0; i < NUM_PIECES; i++) {
  -      print('PIECE $i:============');
  -
         // clone the original piece
         var clone = pieces[i][0].body.map((e) => e).toList();
  -      print(clone);
  -      // print('$i. ${pieces[0][0]}');
   
         for (var j = 1; j < NUM_ROTATIONS; j++) {
           clone = rotate(clone);
  -        print(clone);
           if (pieces[i][j] != null) {
  -          print('removed');
             pieces[i].removeAt(j);
           }
           pieces[i][j] = Piece(i, j, pieces[i][0].color, clone);
         }
  -      print('');
  -    }
  -    assert(pieces.length == NUM_PIECES);
  -    for (var p in pieces) {
  -      assert(p.length == NUM_ROTATIONS);
       }
     }
   
  
positive.code:     apt[3].y = 1;
      pieces[6][0] = Piece(6, 0, RGB(220, 180, 255), apt);
  
      // print('before: ${pieces[0][0]}');
      // Create piece rotations
      rotateAll();
      // print('after rotate: ${pieces[0][0]}');
    }
  
    Piece getPiece(int id, int rotation) {
      assert(!(id >= NUM_PIECES ||
          id < 0 ||
          rotation >= NUM_ROTATIONS ||
          rotation < 0));
  
      if (id >= NUM_PIECES ||
          id < 0 ||
          rotation >= NUM_ROTATIONS ||
  
negative.code:       pt.y = apt[i].x;
        rotated.add(pt);
      }
      return rotated;
    }
  }
  