Because some are paid by amount of lines, so checks you can sell as maybe necessary come in handy. Also giveaway for this is 3 lines for the test instead of one.

Thank you for your comment.

I put this solution to solve the kata only and didn't think about best solutions.

Your piece of code is really clear and I already put it in my toolbox. (y)

I'll try to use your solution in the next time.