how that books
[ '*_deny', 'books_allow', 'movies_deny' ] return false in fixed test however it should return true as in array there is exisit 'books_allow' element?

More difficult than it seems at first glance! But still fun!

The matrix multiplication kata you did is absurdly overranked.

Fixed.

Fixed.

Fixed.

I'm pretty sure it's bugged. I turned user_info into a list, but the list.sort() method didn't work until I typed "reverse = False"

it should definitely be in the specs. examples are not specs.

the description should be correct, complete and consistent without the examples.

Okay, it is pretty clear in the examples. I admit I skimmed over them. But a tiny line could be added to the description when it's talking about precedence for other things.

Python updated; around half the solutions did get invalidated.

that is in the last example, but it's not in the specs - and it should be. examples are not specs.

Maybe the description should say that *_allow loses to *_deny. Or at least that's how it seemed to me and what I wrote in my solution

Both are possible actually; it should be specified. False makes sense though; allow has to be an explicit permission, the default is deny and that overrides allow.

To prevent solutions from being invalidated, keep the current behaviour.

removed from description by Johan

• We should add it to sample and random tests
• ref sol in Python returns False on empty set, it should be True instead, no?