Allow redefinition of class attribute as an instance attribute in a child class

Feature

It is a common design pattern in Python to define a class attribute which functions as a default instance method and can be "overwritten" by instances. For example, in cmd.Cmd

class Cmd:
    prompt = '> '
    ...

If a user were to define a subclass thus

class MyCmd(cmd.Cmd):
    @property
    def prompt(self):
        if self.some_condition():
            return '$ '
        else:
            return '> '

    @prompt.setter
    def prompt(self, value: str) -> None:
        raise NotImplementedError
    ...

mypy would complains,

error: Signature of "prompt" incompatible with supertype "Cmd"

Pitch

Short of changing the superclass (which, in this case, would mean changing the standard library), is there a way that mypy could recognize the above example as a proper child of the parent class?

No files, tests, or implementation entry points are named. Start by reproducing the reported mypy error with the Cmd and MyCmd examples, then locate the superclass compatibility check involved. Done means mypy accepts the child property while preserving the intended type-checking behavior.