Would't that include the 0 rank?

It was weird as my code with global vars works in VS Code but did not pass tests online. Can you recommend a good article to read how to use global vars correctly? Thanks.

I don't see "don't use global variables" in the instructions... May the instructions should be updated?

Aside from the concatenation issue on zip(*board), it returns False when a solution is True..
can't seem to figure out a fix in Python 3

This solution is for old kata without parenthesis.

I tried to run old solutions and they fall if sting has parenthesis. I think kata's Sensei obrok would start a new kata instead for new tests with parenthesis.

In VS Code Python 3.9.4 Win 10:

Calculator().evaluate("( ( ( ( 1 ) * 2 ) ) )")
return float(str_list[0])
ValueError: could not convert string to float: '('

Not working for me in VS Code Python 3.9.4 Win 10:

Calculator().evaluate("3 * ( 4 + 7 ) - 6")
self.result[i - 1] = str(self.operands[x](float(self.result[i-1]), float(self.result[i + 1])))
ValueError: could not convert string to float: '('

cheater :D

Now I see my misstake :-) Thanks!

It's probably not a kata issue, but an error on your side. It seems that you expect l[j-1] and l[j+1] to be convertible to int, but they are not (one of them is "1.1").

If I remember right, the solution was written in Python 2. In that version of Python zip() returns a list. In Python 3 zip() returns a zip object instead, so you will need to convert it into list in order to concatenate it with lists.
board + [*zip(*board)] + blocks can help resolve this.