Python 3.x 当输入错误时，基本计算器错误消息应该出现，但不管输入如何都会出现

我不熟悉编码，决定做一个基本的计算器。在我做了它并开始工作之后，我决定做一个文本，当你输入错误的变量时，它就会出现。我使用了这段代码，但不管输入什么，它都会运行。任何修复都将不胜感激

while user_input != ("1","2","3","4"):
    print("Please enter 1, 2, 3 or 4!")
    user_input = input("Choice:")

以下是完整的代码：

import time

def Add(x, y):
    return x + y # x is added to y

def Sub(x, y):
    return x - y # x is subtracted by y

def Multiply(x, y):
    return x * y # x is multiplied by y

def Divide(x, y):
    return x / y # x is divided by y

print("Select a function:\n")
print("1.Add\n")
print("2.Sub\n")
print("3.Multiply\n")
print("4.Divide\n") 

user_input = input("Choice:") # user chooses function

while user_input != ("1","2","3","4"):
    print("Please enter 1, 2, 3 or 4!")
    user_input = input("Choice:")

num1 = float(input("Enter first number:")) # user unputs number
num2 = float(input("Enter second number:")) # user inputs second number

if user_input == '1':
    print(num1, "+", num2, "=", Add(num1,num2))

if user_input == '2':
    print(num1, "-", num2, "=", Sub(num1,num2))

if user_input == '3':
    print(num1, "*", num2, "=", Multiply(num1,num2))

if user_input == '4':
    print(num1, "/", num2, "=", Divide(num1,num2))

time.sleep(5) # sleeps for 5 seconds before ending

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因此，您试图将单个值与列表进行比较，您真正想要的是检查用户输入是否不在预期值列表中。试着这样做（注意不在）

while user_input not in ("1","2","3","4"):
    print("Please enter 1, 2, 3 or 4!")
    user_input = input("Choice:")