The diversity of two habitats

Small animals were counted in a garden bed and on a mown lawn, $50$ in each. You will write Simpson's diversity index as a function, find it for both places, and say which is more diverse. Then the program draws the two values.

The idea. $D = 1 - \sum \left(\dfrac{n}{N}\right)^2$. A place where the numbers are even has a larger $D$.

Your tasks.

1. In simpson, return the index $D$ for a list of counts.
2. Set garden_D and lawn_D to the index of each place.
3. Set more_diverse to "garden" or "lawn".