Count elements in a list python

Question

I need to be able to count how many of the string \"O\" is in my list

top_board = [
    [None, None, None, None, None, None, None, None, None],
    [None, None,         


        

Answer 1

Update

sum([sum([1 for x in y if x == "O"]) for y in top_board])

(hadn't notice the nesting...)