from typing import Self, final, reveal_type

@final
class Foo:
    def bar(self, other: Foo) -> bool:
        if isinstance(other, Foo): return True

    def baz(self, other: Self) -> bool:
        #                         ^^^^ Function can implicitly return `None`, which is not assignable to return type `bool` (invalid-return-type)
        if isinstance(other, Foo): return True
        reveal_type(other) # revealed: Never