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

def count_O(l):
    count = 0
    for sublist in l:
        count += sublist.count("O")
    return count


if count_O(top_board) == 0:
    #do something