Как исправить: AttributeError: объект «set» не имеет атрибута «append»

Я пытаюсь сыграть в блэкджек на Python, и всякий раз, когда я делаю максимальную ставку (которая составляет 5000), игра работает отлично, но когда я ввожу что-то отличное от 5000, это выдает мне эту ошибку.

Traceback (most recent call last):
  File "c:\Users\Sufysam.DESKTOP-MTN757F\Desktop\Projects\blackjack.py", line 213, in <module>
    main()
  File "c:\Users\Sufysam.DESKTOP-MTN757F\Desktop\Projects\blackjack.py", line 55, in main
    move = getMove(playerHand, money - bet)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "c:\Users\Sufysam.DESKTOP-MTN757F\Desktop\Projects\blackjack.py", line 201, in getMove
    moves.append('(D)ouble down')
    ^^^^^^^^^^^^
AttributeError: 'set' object has no attribute 'append'

Я попробовал перекрестную проверку с помощью ключа ответа для этого проекта и не нашел ничего неправильного. Я также проверяю все свои переменные и функции, и они тоже проверены.

Вот мой код:

import random, sys


HEARTS = chr(9829)
DIAMONDS = chr(9830)
SPADES = chr(9824)
CLUBS = chr(9827)

BACKSIDE = 'backside'


def main():
    print('''Blackjack:
          
    Rules:
        Try to get as close to 21 without going over.
        Kings, Queens, and Jacks are worth 10 points.
        Aces are worth 1 or 11 points.
        Cards 2 through 10 are worth their face value.
        (H)it to take another card.
        (S)tand to stop taking cards.
        On your first play, you can (D)ouble down to increase your bet
        but must hit exactly one more time before standing.
        In case of a tie, the bet is returned to the player.
        The dealer stops hitting at 17.''')
          
    money = 5000
    while True:
        if money <= 0:
            print('You\'re broke!')
            print("Good thing you weren\'t playing with real money")
            print('Thanks for playing!')
            sys.exit()


        print('Money:', money)
        bet = getBet(money)


        deck = getDeck()
        dealerHand = [deck.pop(), deck.pop()]
        playerHand = [deck.pop(), deck.pop()]


        print('Bet:', bet)
        while True:
            displayHands(playerHand, dealerHand, False)
            print()


            if getHandValue(playerHand) > 21:
                break


            move = getMove(playerHand, money - bet)


            if move == 'D':
                additonalbet = getBet(min(bet, (money - bet)))
                bet += additonalbet
                print('Bet increased to {}.'.format(bet))
                print('Bet:', bet)

            if move in ('H', 'D'):
                    newCard = deck.pop()
                    rank, suit = newCard
                    print('You drew a {} of {}.'.format(rank, suit))
                    playerHand.append(newCard)

                    if getHandValue(playerHand) > 21:
                        continue
            
            if move in ('S', 'D'):
                break
        

        if getHandValue(playerHand) <= 21:
            while getHandValue(dealerHand) < 17:
                print('Dealer hits...')
                dealerHand.append(deck.pop())
                displayHands(playerHand, dealerHand, False)

                if getHandValue(dealerHand) > 21:
                    break
                input('Press Enter to contiue...')
                print('\n\n')


        displayHands(playerHand, dealerHand, True)

        playerValue = getHandValue(playerHand)
        dealerValue = getHandValue(dealerHand)

        if dealerValue > 21:
            print('Dealer busts! You win ${}!'.format(bet))
            money += bet
        elif (playerValue > 21) or (playerValue < dealerValue):
            print(' You lost!')
            money -= bet
        elif playerValue > dealerValue:
            print('You won ${}!'.format(bet))
            money += bet
        elif playerValue == dealerValue:
            print('It\s a tie, the bet is returned to you')
        
        input('Press Enter to continue...')
        print('\n\n')


def getBet(maxBet):
    while True: 
        print('How much do you bet? (1-{}, or QUIT)'.format(maxBet))
        bet = input('> ').upper().strip()
        if bet == 'QUIT':
            print('Thanks for playing!')
            sys.exit()

        if not bet.isdecimal():
            continue

        bet = int(bet)
        if 1 <= bet <= maxBet:
            return bet
        

def getDeck():
    deck = []
    for suit in (HEARTS, DIAMONDS, SPADES, CLUBS):
        for rank in range(2, 11):
            deck.append((str(rank), suit))
        for rank in ('J', 'Q', 'K', 'A'):
            deck.append((rank, suit))
    random.shuffle(deck)
    return deck


def displayHands(playerHand, dealerHand, showDealerHand):
    print()
    if showDealerHand:
        print('Dealer: ', getHandValue(dealerHand))
    else:
        print('Dealer : ???')

        displayCards([BACKSIDE] + dealerHand[1:])


    print('PLAYER:', getHandValue(playerHand))
    displayCards(playerHand)


def getHandValue(cards):
    value = 0
    numberofAces = 0


    for card in cards:
        rank = card[0]
        if rank =='A':
            numberofAces += 1
        elif rank in ('K', 'Q', 'J'):
            value += 10
        else:
            value += int(rank)


    value += numberofAces
    for i in range(numberofAces):
        if value + 10 <= 21:
            value += 10

    return value

def displayCards(cards):
    rows = ['', '', '', '', '']

    for i, card in enumerate(cards):
        rows[0] += ' ___ '
        if card == BACKSIDE:
            rows[1] += '|## | '
            rows[2] += '|###| '
            rows[3] += '|_##| '
        else:
            rank, suit = card 
            rows[1] += '|{} | '.format(rank.ljust(2))
            rows[2] += '| {} | '.format(suit)
            rows[3] += '|_{}| '.format(rank.rjust(2, '_'))



    for row in rows:
        print(row)

        
def getMove(playerHand, money):
    while True:
        moves = {'(H)it', '(S)tand'}



        if len(playerHand) == 2 and money > 0:
            moves.append('(D)ouble down')


        movePrompt = ', '.join(moves) + '> '
        move = input(movePrompt).upper()
        if move in ('H', 'S'):
            return move
        if move == 'D' and '(D)ouble Down' in moves:
            return move
        

if __name__ == "__main__":
    main()