Three Dollar Quill

@attrs.frozen
class Coerce[T]:
    ctor: Callable[[type[T]], T]

    def __get__(
        self, instance: T | None, owner: type[T]
    ) -> Callable[, Constraints[Bundle[T]]]:
        def coerce(type_bundle: Bundle[Any]) -> Constraints[Bundle[T]]:
            typ = type_bundle.data
            if isinstance(typ, owner):
                return Bundle(typ, type_bundle.metadata)
            yield from ()
            return type_bundle.extend(
                lambda n: self.ctor(owner),
                CoercionFailure(),
            )
        return coerce