def test_4(self):
compressed_img = "xxwwwbxwxwbbbwwxxxwwbbbwwwwbb"
self.assertEqual(quadtree_to_img(img_to_quadtree(compressed_img)), compressed_img)
def test_3(self):
self.assertEqual(quadtree_to_img(img_to_quadtree("xbwxwbbwb")), "xbwxwbbwb")
