I would do

class MyClass:
    def __init__(self, value):
        self._whatever = value

    @property
    def whatever(self):
        return self._whatever

Personally, I would type hint all of that but I'm just showing how you can do it without types. Your linter should be smart enough to say "hey dumbass did you mean this other thing"? Also since we didn't create a setter you can't arbitrarily overwrite the value of whatever so thats neat.

And I'll just say before I post that I'm on mobile and I'm sorry if the formatting is fucked. I'm not going to fix it.