Python中的Tic-tac-toe计算机，无效语法问题

class TicTacToe:
    def __init__(self):
        self.board = [[' ' for _ in range(3)] for _ in range(3)]
        self.current_player = 'X'

    def print_board(self):
        for row in self.board:
            print('|'.join(row))
            print('-' * 5)

    def make_move(self, row, col):
        if self.board[row][col] == ' ':
            self.board[row][col] = self.current_player
            self.current_player = 'O' if self.current_player == 'X' else 'X'
        else:
            print("Invalid move! Please try again.")

    def check_winner(self):
        # Check rows
        for row in self.board:
            if row[0] == row[1] == row[2] != ' ':
                return row[0]

        # Check columns
        for col in range(3):
            if self.board[0][col] == self.board[1][col] == self.board[2][col] != ' ':
                return self.board[0][col]

        # Check diagonals
        if self.board[0][0] == self.board[1][1] == self.board[2][2] != ' ':
            return self.board[0][0]
        if self.board[0][2] == self.board[1][1] == self.board[2][0] != ' ':
            return self.board[0][2]

        return None

# 游戏示例
game = TicTacToe()
game.make_move(0, 0)
game.make_move(1, 1)
game.make_move(0, 1)
game.make_move(1, 2)
game.make_move(0, 2)
game.print_board()
winner = game.check_winner()
if winner:
    print("Winner:", winner)
else:
    print("It's a tie!")