Tic-tac-toe错误。 str对象整数

Question

def new_board():
    """Create new game board."""
    board = []
    for square in range(NUM_SQUARES):
        board.append(EMPTY)
    return board

错误：

TypeError: 'str' object cannot be interpreted as an integer

我正在用Python编程，我正在尝试编写一个tic-tac-toe程序。我该怎么办？