def foo(return_more: bool) -> Union[Type1, tuple[Type2,Type3]]:
it’s another way to violate your privacy.
take a look at subtree, it incorporates the history of the upstream repository into your repository easily and if the upstream vanishes one day, you would still have a full repo history of upstream
Couple of others have suggested to Submodules. git subtree is another alternative. Personally, I felt subtree much more easier to use.
or a very nutty Pet Detective in Asylum.