You are given the length and width of a 4-sided polygon. The polygon can either be a rectangle or a square.
If it is a square, return its area. If it is a rectangle, return its perimeter.
area_or_perimeter(6, 10) --> 32
area_or_perimeter(4, 4) --> 16
Want to propose a challenge idea for a future post? Email email@example.com with your suggestions!