In this set of exercises, you will build up images of ice cream cones.
The teachpack provides an image of an empty ice-cream cone (called
empty-cone).  Scoops of ice cream can be drawn as circles.  Using the
overlay/xy operation on images, you can add new scoops to the top of
existing cones.

1. Create a struct for ice cream flavors.  A flavor contains the color
of the flavor and a boolean indicating whether the flavor includes
chocolate chips.

2. Write a function create-scoop that consumes a flavor and produces
an image of a scoop of ice cream in that flavor.  (A circle of radius
25 works well with the cone size -- use a constant for the scoop
size.)

Your answer should use helper functions to avoid duplicating
computations.  You may also want a helper for adding chips.  Use small
rectangles to draw chips when appropriate.
 
3. Write a function add-scoop that consumes a flavor and an image of a
cone (with or without ice cream already on it) and produces an image
of the cone with the new scoop added to the top.  [hint: you may need
to use center-pinhole (from the teachpack) to put the pinhole of the
cone image in the right place.]

4. Real ice cream scoops are lumpier than plain circles. We can make
our scoops look lumpy by adding a small circle of the same color
hanging off the lower edge of each scoop (and over the scoop or cone
underneath).  Write a function add-fancy-scoop that takes a flavor and
a cone image (with or without ice cream already on it) and produces an
image of the cone with a lumpy scoop of that color on top.

5. Write a function cone-price that consumes a cone image and produces
the price of the cone.  An empty cone costs $1 and each additional
scoop costs 75 cents (the chips are free).  Use the height of the
empty cone and scoop images to figure out the price.

Bon appetit!