The boxes you need

Problem

You're packing books into boxes, and each box holds per_box books. Write a function that takes how many books there are and how many fit in a box, and returns how many boxes you need to pack them all.

The last box can go half empty and you still have to buy it:

9 books at 4 per box need 3 boxes.

If there are no books, you need no boxes.

Examples

• 9, 4 → 3

• An exact fit

  12, 4 → 3

• Fewer books than the box holds

  3, 5 → 1

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def boxes(books, per_box):
    pass

function boxes(books, perBox) {
}