Write a function named parts that will take in as parameters the dimensions of the box (length, width, and height) and the radius of the hole, and returns the volume of material remaining. Assume the hole has been drilled along the height direction. Note: first write the function assuming the hole has radius less than min(length/2, width/2). For full credit, you will need to account for larger radii (bigger than half the length or width of the box).