Mein Tic-Tac-Toe-Python-Spiel endet nicht, wenn ein Spieler gewinnt

Schönen Tag. Ich lese gerade Michael Dawsons Buch Python für den absoluten Anfänger . Ich habe diesen Code für Kapitel 6 und wenn ich den Code ausgeführt habe und das gerade "X" im Board habe, wird der Gewinner nicht zurückgegeben. Das Programm wird fortgesetzt, bis alle Leerzeichen entweder mit "X" oder "O" markiert sind. Hier ist mein Code:

#!/usr/bin/python3
X = "X"
O = "O"
EMPTY = " "
TIE = "TIE"
NUM_SQUARES = 9

def display_instruct():
    print(
          """
          Welcome to the greatest intellectual challenge of all time: Tic-Tac-Toe.
          This will be a showdown between your human brain and my silicon processor.

          You will make your move known by entering a number, 0 - 8. The number
          will correspond to the board position as illustrated:

                                      0 | 1 | 2
                                     -----------
                                      3 | 4 | 5
                                     -----------
                                      6 | 7 | 8

            Prepare your self, human. The ultimate battle is about to begin. \n
            """)

def ask_yes_no(question):
    response = None
    while response not in ("y", "n"):
        response = input(question).lower()
    return response

def ask_number(question, low, high):
    response = None
    while response not in range(low, high):
        response = int(input(question))
    return response

def pieces():
    go_first = ask_yes_no("Do you require the first move? (y/n): ")
    if go_first == "y":
        print( "\nThen take the first move. You will need it. ")
        human = X
        computer = O
    else:
        print("\nYour bravery will be your undoing... I will go first.")
        computer = X
        human = O
    return computer, human

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

def display_board(board):
    print("\n\t", board[0], "|", board[1], "|", board[2])
    print("\t", "---------")
    print("\t", board[3], "|", board[4], "|", board[5])
    print("\t", "---------")
    print("\t", board[6], "|", board[7], "|", board[8], "\n")

def legal_moves(board):
    moves = []
    for square in range(NUM_SQUARES):
        if board[square] == EMPTY:
            moves.append(square)
    return moves

def winner(board):
    WAYS_TO_WIN = ((0, 1, 2),
                   (3, 4, 5),
                   (6, 7, 8),
                   (0, 3, 6),
                   (1, 4, 7),
                   (2, 5, 8),
                   (0, 4, 8),
                   (2, 4, 6))

    for row in WAYS_TO_WIN:
        if board[row[0]] == board[row[1]] == board[row[2]] != EMPTY:
            winner = board[row[0]]
            return winner

        if EMPTY not in board:
            return TIE

        return None

def human_move(board, human):
    """Get human move."""
    legal = legal_moves(board)
    move = None
    while move not in legal:
        move = ask_number("Where will you move? (0 - 8): ", 0, NUM_SQUARES)
        if move not in legal:
            print("\nThat square is already occupied, foolish human. Choose another.\n")
    print("Fine....")
    return move

def computer_move(board, computer, human):
    """Make computer move."""
    #make a copy to work with since function will be changing list.
    board = board[:]
    BEST_MOVES = (4, 0, 2, 6, 8, 1, 3, 5, 7)
    print("I shall take square number")

    # if computer can win, take that move
    for move in legal_moves(board):
        board[move] = computer
        if winner(board) == computer:
            print(move)
            return move
        board[move] = EMPTY

    # if human can win, block that move
    for move in legal_moves(board):
        board[move] = human
        if winner(board) == human:
            print(move)
            return move
        # done checking this move, undo it
        board[move] =  EMPTY

    # since no one ca win on next move, pick best open square
    for move in BEST_MOVES:
        if move in legal_moves(board):
            print(move)
            return move

def next_turn(turn):
    if turn == X:
        return 0
    else:
        return X

def congrat_winner(the_winner, computer, human):
    if the_winner != TIE:
        print(the_winner, "won!\n")
    else:
        print("It's a tie!\n")
    if the_winner == computer:
        print("As I predicted, human, I am triumphant once more. \n" \
              "Proof that computers are superior to humans in all regards.\n")

    elif the_winner == human:
        print("No, no! It cannot be! Somehow you tricked me, human. \n" \
              "But never again! I, the computer, so swears it\n!")

    elif the_winner == TIE:
              print("You were most lucky, human, and somehow managed to tie me. \n" \
                    "Celebrate today... for this is the best you will ever achieve.\n")

def main():
    display_instruct()
    computer, human = pieces()
    turn = X
    board = new_board()
    display_board(board)

    while not winner(board):
        if turn == human:
            move = human_move(board, human)
            board[move] = human
        else:
            move = computer_move(board, computer, human)
            board[move] = computer

        display_board(board)
        turn = next_turn(turn)

    the_winner = winner(board)
    congrat_winner(the_winner, computer, human)

main()

input("Press enter to exit")