nope, but that avoids the hassle of maintaining the related property when changes are done to one of the others.

note: the explanation is written just below... ;p

is it necessary to use object decorator?

Same for me.
I was wonder if the the challenge is to find as quickly as possible a big prime number list or smth else ...

it's not "needed", but it's a better design (less storage, and no "duplicated data" stored). As usual, it's a trade off, ofc: no redundant data, but more "costy" since it needs some computations to get the actual data.

Same here. I can't understand what are we supposed to do here!

The first instruction creates the module and the second returns it.
You can notice in the test's code that your module is imported by using the "require" keyword.

The description is still lacking in the Python translation at least.

I like how readable the chunking is in this solution.

Would be useful to add this to the test cases then.

I would suggest rewording the instructions as it's not immediately obvious what the logic is supposed to be implemented. Personally I would also do without the obnoxiously long return values.

What are the lines kata = {} and return kata doing ?