使用Python 3.8并给出这些行：

from enum import Enum

class Stuff1(str, Enum):
    A = "A"
    B = "B"
    C = "C"

class Stuff2(int, Enum):
    A = 1
    B = 2
    C = 3

def encoder(value: <?>) -> str:
    return value.value.lower()

a = encoder(Stuff1.A) # Will work as expected because Stuff1 is expected as input
b = encoder(Stuff2.B) # Will not work but will not be a warning inside my IDE if <?> is Enum

如何键入hint包含字符串值的枚举来代替<？>，是否只授权Stuff1内部编码器参数？我希望这个值是一个枚举，但我希望这个枚举只有字符串值。实现这一目标的最佳途径是什么？
注意：是的，在Python 3.11中存在StrEnum，但我在Python 3.8下
NB 2：我应该能够在不知道Enum中的值的情况下输入我的参数，所以Literal不适合我。
我目前有：

from enum import Enum

def encoder(value: Enum) -> str:
    if isinstance(value, str):
        return value.value.lower()
    raise Exception("Non string value as input")

a = encoder(Stuff1.A) # Will work as expected and my IDE will be happy because Stuff1 is expected as input
b = encoder(Stuff2.B) # Will not be a warning inside my IDE as Stuff2 is an Enum too, but contains integers.

但是我只需要字符串值Enums，所以对于简单的东西来说，这段代码看起来有点沉重。