In your example, you can't use `Rectangle(1, 1)` as a Square which was the point of the author. No a square is not a rectangle, it's a shape that have common p

In your example, you can't use `Rectangle(1, 1)` as a Square which was the point of the author. No a square is not a rectangle, it's a shape that have common properties to other shapes (rectangles, diamonds, ...).