使用循环更改二维列表中的多个值

我正在编写的程序是在将座位创建为5行5列的二维列表后，在剧院中“出售”座位。我已经将其大部分工作了，但是如果我在标记为已售出的座位旁边选择一个座位，则会收到一条信息，好像该座位也已售出一样。这是我使用的标准：

填充5 x 5网格。然后执行以下操作。创建一个循环，该循环将一直持续到用户说出他们要退出（是/否）或全部25个席位售出为止。让用户根据行和列（行，列）询问座位位置-记住列表的位置从0开始，但是用户会从行或列位置1询问座位。然后，当用户选择座位，打印出用户的价格，并在价格所在的列表中标记一个“ SS”（已售座位）。然后打印出所有座位，以便用户选择其他座位。当循环中的下一个用户要求座位时，请确保您检查并查看该座位是否已售出（表中有“ SS”）。如果已售出，请告知用户-否则退还价格并标记售出的座椅。在用户要求退出或所有席位都售完或循环结束之后，

这是我的代码：

def main():
seatList = [
    [50,50,50,50,50],
    [40,45,45,45,40],
    [30,35,35,35,30],
    [20,20,20,20,20],
    [10,10,10,10,10],
]
cont = "y"
while cont.lower() == "y":
    print("Here is the seating arrangement:")
    availableSeat = seatPrinter(seatList)
    totalRow = int(len(seatList)) - 1
    totalColumn = int(len(seatList[0])) - 1
    seatRow = int(input("Please enter a row number (1 to %d):"%totalRow))
    seatColumn = int(input("Please enter a seat number (1 to %d):"%totalColumn))
    seatStatus = seatAvailable(seatList, seatRow, seatColumn)
    cont = input("Would you like to reserve another seat?(Y/N)")

def seatPrinter(seats):
    for i in range(len(seats[0])):
        print(seats[i])

def seatAvailable(seats, row, column):
    for i in range(len(seats)):
        for j in range(len(seats)):
            if seats[i][j] is not 'SS':
                seats[i][j] = 'SS'
                print("Your seat is in row %d seat number %d"%(i+1, j+1))
                return
            else:
                print("Sorry, that seat isn't available.")
                return

main()

现在，这是我得到的输出：

Here is the seating arrangement:
[50, 50, 50, 50, 50]
[40, 45, 45, 45, 40]
[30, 35, 35, 35, 30]
[20, 20, 20, 20, 20]
[10, 10, 10, 10, 10]
Please enter a row number (1 to 4):1
Please enter a seat number (1 to 4):1
Your seat is in row 1 seat number 1
Would you like to reserve another seat?(Y/N)y
Here is the seating arrangement:
['SS', 50, 50, 50, 50]
[40, 45, 45, 45, 40]
[30, 35, 35, 35, 30]
[20, 20, 20, 20, 20]
[10, 10, 10, 10, 10]
Please enter a row number (1 to 4):1
Please enter a seat number (1 to 4):2
Sorry, that seat isn't available.
Would you like to reserve another seat?(Y/N)

我似乎找不到为什么我不能在同一排预订更多座位，感谢您的帮助