> type Vertex = (Float,Float)

> data Shape = Rectangle Vertex Vertex
>            | Polygon [Vertex]
>            | Polyline [Vertex]
>            | Ellipse Vertex Vertex
>            | ShearEllipse Vertex Vertex Vertex

> data Pic1 = EmptyPic1
>           | Above1 Pic1 Pic1
>           | Prim1 Shape
>           | WithColor1 Color Pic1

Produce an instance of Eq for Pic1 that respects the
equalities involving emptyPic and withColor, in particular:

< WithColor1 c1 (WithColor1 c2 p) == WithColor1 c2 p  =  True


> data Pic2 = EmptyPic2
>           | Above2 Pic2 Pic2
>           | Prim2 {shape :: Shape
>                   ,color :: Color
>                   }
>           | Move2 Pic2

Implement the following conversions:

> pic1FromPic2 :: Pic2 -> Pic1
> pic2FromPic1 :: Pic1 -> Pic2

Implement the following functions without using those conversions:

> graphicFromPic1 :: Pic1 -> Graphic
> graphicFromPic2 :: Pic2 -> Graphic

> move1 :: Vertex -> Pic1 -> Pic1
> move2 :: Vertex -> Pic2 -> Pic2

> withColor1 :: Color -> Pic1 -> Pic1
> withColor2 :: Color -> Pic2 -> Pic2

> prim1 :: Shape -> Pic1
> prim2 :: Shape -> Pic2

> above1 :: Pic1 -> Pic1 -> Pic1
> above2 :: Pic2 -> Pic2 -> Pic2

Implement instances of the following class for Pic1 and Pic2:

> class Picture p where
>   prim           :: Shape       -> p
>   move           :: Vertex -> p -> p
>   withColor      :: Color  -> p -> p
>   above          :: p      -> p -> p
>   graphicFromPic :: p           -> Graphic

Add a scaling function to this class and its instances.

Use the extended class to implement a function that, when invoked with

< sierpinski size d

delivers a  ``Picture'' Sierpinski triangle with outer side length
size and recursion depth d:

> sierpinski :: Picture p => Double -> Int -> p

Perform experiments using graphicFromPic.