// TODO - write your code below this comment.
// You need to do the following:
//
// 1.) Define a class named CirclePrecomputedArea.
//     This class inherits from Circle.
//
// 2.) Define an instance variable named area, which
//     holds a double.
//
// 3.) Define a constructor which takes a double
//     to initialize the superclass with.
//     You'll need to use super.  Additionally,
//     you'll need to set area to the area of this
//     circle, using the same expression as you
//     used in CircleDynamicArea
//
// 4.) Define getArea to simply return the value
//     in the area instance variable (just like
//     a normal getter)
//
// 5.) Override the setRadius method to recompute
//     the value of the area, after setting the
//     radius of the circle to the new value.
//     You'll need to call the superclass' setRadius
//     method with super.
//