我收到 EOF 错误，我正在努力修复它

问：

当我在

operation = input("what do you want to do (+,-,/,*):")

代码如下

def add(num1, num2): #function signature
    return num1 + num2

def sub(num1, num2): #function signature
    return num1 - num2

def div(num1, num2): #function signature
    return num1 / num2

def mul(num1, num2): #function signature
    return num1 * num2


def main():
    operation = input("what do you want to do (+,-,/,*):")
    if(operation != '+' and operation != '-' and operation != '/' and operation != '*'):
       print("you must enter a valid operation")
    else:
        var1 = int(input("Enter num1: "))
        var2 = int(input("Enter num2: "))
        if(operation == '+'):
            print(add(var1, var2))
        elif (operation == '-'):
            print (sub(var1, var2))
        elif (operation == '/'):
            print (div(var1, var2))
        else:
            print (mul(var1, var2))
main()

这是错误！

File "<string>", line 1
    +
    ^
SyntaxError: unexpected EOF while parsing