There's a problem with this code when the game ties at the end. Can you figure it out?

import random

X = "X"

O = "O"

EMPTY = " "

TIE = "TIE"

NUM_SQUARES = 10

def ask_yes_no(question):

"""Ask a yes or no question."""

response = None

while response not in ("y", "n"):

response = input(question).lower()

return response

def ask_number(question, low, high):

"""Ask for a number within a range."""

response = None

while response not in range(low, high):

response = int(input(question))

return response

def pieces():

print('Randomly picking a player to go first...')

# generating a random integer, either 0 or 1

ch = random.randint(0, 1)

if ch == 0:

print(" Great! You have the first move.")

human = X

computer = O

else:

print(" Looks like I'm gonna 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(" \t", board[1], "|", board[2], "|", board[3])

print("\t", "---------")

print("\t", board[4], "|", board[5], "|", board[6])

print("\t", "---------")

print("\t", board[7], "|", board[8], "|", board[9], " ")

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 = ((1, 2, 3),

(4, 5, 6),

(7, 8, 9),

(1, 4, 7),

(2, 5, 8),

(3, 6, 9),

(1, 5, 9),

(3, 5, 7))

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):

legal = legal_moves(board)

move = None

while move not in legal:

move = ask_number("Where will you move? (0 - 8):", 1, NUM_SQUARES)

if move not in legal:

print(" That square is already occupied, foolish human. Choose another. ")

print("Fine... ")

return move

def computer_move(board, computer, human):

# make a copy to work with since function will be changing list

board = board[:]

# the best positions to have, in order

BEST_MOVES = (5, 1, 3, 7, 9, 2, 4, 6, 8)

print("I shall take square number", end=" ")

# if computer can win, take that move

for move in legal_moves(board):

board[move] = computer

if winner(board) == computer:

print(move)

return move

# done checking this move, undo it

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 checkin this move, undo it

board[move] = EMPTY

for move in BEST_MOVES:

if move in legal_moves(board):

print(move)

return move

def next_turn(turn):

"""Switch turns."""

if turn == X:

return O

else:

return X

def congrat_winner(the_winner, computer, human):

if the_winner != TIE:

print(the_winner, "won! ")

else:

print("It's a tie! ")

if the_winner == computer:

print("I predicted as much. ")

elif the_winner == human:

print("No ")

elif the_winner == TIE:

print("Lucky ")

def main():

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)

if __name__ == '__main__':

main()

input(" Press the enter key to quit.")