怎么用calculate表示多个计算符号

他让定义一个计算符号变量，但是不会定义，希望能帮帮我如果没错的话应该是用if-else语句吧

mum1 = eval(input("请输入num1的值:"))
calculate = input("请输入运算符:")
mum2 = eval(input("请输入num2的值:"))
if calculate == "+":
    print("mum1{}mum2={}".format(calculate, mum1 + mum2))
elif calculate == "-":
    print("mum1{}mum2={}".format(calculate, mum1 - mum2))
elif calculate == "*":
    print("mum1{}mum2={}".format(calculate, mum1 * mum2))
elif calculate == "/" and mum2 != 0:
    print("mum1{}mum2={}".format(calculate, mum1 /mum2))
elif calculate == "/" and mum2 == 0:
    print("mum2的值不能等于0")
else:
    print("你输入的运算符为:{}请输入正确的运算符!".format(calculate))

c=input()不就行了，你想输入什么输入什么，它就是个字符串

calculate = input('输入符号')
a = 1
b = 2
if calculate == '+':
    ret = a + b
elif calculate == '-':
    ret = a - b
elif calculate == '*':
    ret = a * b
elif calculate == '/':
    ret = a / b