Ref T4334. This implements a new node type for type hints in general, and uses them to add nullability to a type hint.
Added test cases.
Remove copy-flag from new unit test (caused by copy-via-IDE)
For real now :(
This does not appear to have any impact on arc/lint.
(This and the other change look good to me, I just want to look at them in more detail and maybe take a stab at fixing the awful unreadable test cases while we're here.)
Sure, no problem. Let me know if there is something I can do to help