Python code for a game of Tic Tac Toe

tic_tac_toe.py

BOARD = dict()
EMPTY_CHAR = "*"
WIN_CHAR = "@"

# Store all possible win combinations
WIN_COMBOS = [
    (1, 2, 3), 
    (4, 5, 6),
    (7, 8, 9),
    (1, 4, 7),
    (2, 5, 8),
    (3, 6, 9),
    (1, 5, 9),
    (3, 5, 7),
]

def setup_game():
    # Initialize the board with empty states. We're using a simple dictionary with indices running from 1 through 9
    # |1 2 3|
    # |4 5 6|
    # |7 8 9|
    for i in range(1, 10):
        BOARD[i] = EMPTY_CHAR


def check_win():
    # Check if either player won the game
    for i, j, k in WIN_COMBOS:
        if BOARD[i] == BOARD[j] == BOARD[k] != EMPTY_CHAR:
            winner = BOARD[i]
            BOARD[i] = BOARD[j] = BOARD[k] = WIN_CHAR
            return winner
    return None


def continue_game():
    # The game can continue if there's an empty spot
    if EMPTY_CHAR in BOARD.values():
        return True
    return False


def next_turn(current_turn):
    # Swap turns between the two players, X & O
    if current_turn == "X":
        return "O"
    else:
        return "X"


def print_board(show_index=False):
    # Print the board's current state
    for i in range(1, 10,):
        if i % 3 == 1:
            print("|", end=' ')
        if show_index:
            # Print the cell indices
            print(i, end=' ')
        else:
            # Print the actual board
            print(BOARD[i], end=' ')
        if i % 3 == 0:
            print("|", end=' ')
            print()


def get_input(turn):
    # Get user input on which cell they want to play
    valid = False
    while not valid:
        try:
            num = int(input("Enter a number: "))
            assert 1 <= num <= 9
        except (ValueError, AssertionError):
            print("Please enter a valid number between 1 and 9.")
            continue

        if BOARD[num] == EMPTY_CHAR:
            BOARD[num] = turn
            valid = True
        else:
            print("That cell has already been played, try again.")


def play():
    print("Welcome to the game of Tic Tac Toe.")
    print("The board is set up with numbers corresponding the the 9 positions.")
    print_board(show_index=True)
    print("To make a move, enter the cell number on your turn.")
    turn = "X"
    winner = None

    while continue_game():
        print_board()
        nxt = next_turn(turn)
        get_input(turn)
        winner = check_win()
        if winner:
            print("Player {} has won the game".format(winner))
            print_board()
            break
        turn = nxt
    if winner is None:
        print("The game was drawn, well played both :)")


if __name__ == "__main__":
    setup_game()
    play()