All my tests except one last test work and I don't even know what's wrong with it.

Why didn't you print the input? When you have problems, think to print (kind of debugging).

Sorry but I can't make it more explicit or it could be as well to give the solution...

show examples of empty lists or None and what they should actually return

Such examples would give part of the solution because there are not many cases where that can happen!

You are new at CW, you will see that doing a kata demands some thinking, tries and errors, it is life!
Moreover notice that 35827 people passed the kata (with problems of course, that goes without saying) despite what you call a poor wording. As to the "self-evident" part, it is "self evident" since you could have thought of the lengths of a and b to have a better understanding.
I'm sorry I can't give you satisfaction.

Can we please make kata description better, show examples of empty lists or None and what they should actually return?

If a or b are empty then the result is self-evident.

"a or b are empty or not empty lists."

Am I supposed to return string "a or b are empty or not empty lists."? All my tests except one last test work and I don't even know what's wrong with it. Is it possible that last test (for Python) is wrong? Or I don't understand the task correctly.

UPD: Somehow managed to complete it and I'm not even sure what I was doing wrong, but description is worded poorly IMHO (sorry, author, no offence), no real examples of empty lists or None objects, no explanation of arrays of different length, and self-evident part was not self-evident to me at all. Please make the task clear next time.

Thaks i finally did it done . For junior such me remarks at the bottom of description was too hard. I wasted to deal with it 10x times more than with task itself.

It just doesn't work like that... There's no magic here. Maybe the last assertion text is with nil arrays and they don't get displayed in console (IDK how go handles that). I edited your code and it works, you just need to read what error messages tell you and react to them.

As a little hint: you can replace 6 if statements at top with 2: 1 that deals with nil values and 1 that deals with different array lengths. Good luck.

no: {2, 2, 3} => {2x2, 2x2, 3x3} => {4, 4, 9} != {4, 9, 9}

Spoiler flag, please.

What sorcery is this?