It should work with the Python 3 syntax if you quote your type annotation. I.e. def f() -> "Bar": ... instead of def f() -> Bar: ... (This is normally

It should work with the Python 3 syntax if you quote your type annotation. I.e. def f() -> "Bar": ... instead of def f() -> Bar: ... (This is normally used for forward references.) This makes it slightly less nice, but not a terrible workaround overall.