"TypeError:'NoneType'类型的参数不可迭代"？

Question

下面是我编写的一些Python代码,用于生成一个随机的扑克手,只是为了它/它的挑战,但当我尝试运行它时,我得到上面的错误"如果卡在手".发生了什么,为什么会发生这种情况,特别是因为那条线没有迭代？

import random
def pokerHand():
    hand = ["This is your hand:"]
    x = 0
    while x < 5:
        cardNum = random.randrange(13) + 1
        if cardNum == 1:
            cardNum = "Ace of "
        elif cardNum == 11:
            cardNum = "Jack of "
        elif cardNum == 13:
            cardNum = "King of "
        elif cardNum == 12:
        cardNum = "Queen of "
        else:
            cardNum = str(cardNum) + " of "
        cardSuit = random.randrange(4)
        if cardSuit == 0:
            cardSuit = "Clubs"
        elif cardSuit == 1:
            cardSuit = "Diamonds"
        elif cardSuit == 3:
            cardSuit = "Hearts"
        elif cardSuit == 2:
            cardSuit = "Spades"
        card = cardNum + cardSuit
        if card in hand: #<the line of error
            pass
        else:
            hand = hand.append(card)
            x = x + 1
    for xx in hand:
        print xx

Answer 1

hand = hand.append(card)

append没有任何回报.将其更改为:

hand.append(card)