Now it works.
Thank you!

It expects a list as response, it also sometimes passes a list of numbers instead of the actual numbers, I worked around that but it still expects a list as a result in some tests...

Tests are broken in python 3 at least...

I still see "You can truncate it to 9 decimal places."

It isn't worded appropriately: it should be "you MUST truncate" not "you can truncate"

But you're rounding rather than truncating, how does it pass the tests?
Can someone explain me?

Take a look at my two-liner.

The time complexity of this is O(n * m) and can be solved in O(n + m)

But if the function gets called like last("hi", "bye") this would return "e" and from what I understood this should return "bye" with that input.
It seems the kata needs more tests or clarify that in the instructions.

But if the function gets called like last("hi", "bye") this would return "e" and from what I understood this should return "bye" with that input.
It seems the kata needs more tests or clarify that in the instructions.

Oh I see, thanks for explaining this to me.

Here is a good article to learn about time complexity:
https://towardsdatascience.com/understanding-time-complexity-with-python-examples-2bda6e8158a7

Here you can see the time complexity of different methods of Python builtin data structures:
https://wiki.python.org/moin/TimeComplexity

Nice solution

I did it the other way around