If you want to try this Kata for yourself or at your dojo meeting, read the problem description and see if the Kata appeals to you. The rest is commentary and helpful clues for if you get stuck solving it. I would recommend trying the Kata for yourself before reading too much of it.
Once upon a time there was a series of 5 books about a very English hero called Harry. (At least when this Kata was invented, there were only 5. Since then they have multiplied) Children all over the world thought he was fantastic, and, of course, so did the publisher. So in a gesture of immense generosity to mankind, (and to increase sales) they set up the following pricing model to take advantage of Harry’s magical powers.
One copy of any of the five books costs 8 EUR. If, however, you buy two different books from the series, you get a 5% discount on those two books. If you buy 3 different books, you get a 10% discount. With 4 different books, you get a 20% discount. If you go the whole h