Oh, completely missed that. Sorry for that.

I think you didn't look at the rigth test. The result of the test is below your printing.

This is one of the best kata I've done in a while. It took me a while to understand and then I ran into a lot of errors and especially hidden bugs. One of the main thing I forgot is to implement a way to tell the machine to forget the command because it turned out to be incorrect. When I saw that it was like a revelation. It's the same idea as to not get traped in your own history, not to cling onto your beliefs and look at the world as it is and not how you want it to be. This seems quite deep but that's what I got after solving this kata. At the end I just want to say thank you for creating this.