# it appends a list into a list list1 = [1,2,3,4,5] list1.append([6,7]) # ouput = [1, 2, 3, 4, 5, [6, 7]]
board = [] for i in range(6): # create a list with nested lists board.append([]) for n in range(6): board[i].append("O") # fills nested lists with data