The formula for the volume of a cylinder is height * area. The formula for the area is PI*radius2. Define the two functions below (calculate_area and calculate_volume) to use these formula to calculate the volume of a cylinder with the given radius and height. Add at least one additional unit test.

Note: It is okay to have PI inside your function definitions, even though it was defined outside. Since PI never changes its value (it is a “constant”), it is okay to access it out of scope.