TYP: read_sas
Does this need documentation because we’re breaking the API or do we consider it internal with no guarantees? > Does this need documentation because we’re breaking the API or do we consider it internal with no guarantees?

If we want this change @jreback  (I certainly would like it from a typing perspective), I think it should have a whatsnew. Otherwise, I'm happy to keep `None` but then adjust the overloads of `read_sas` to include `None` i think it's fine

just add a note on the very slight api change Thanks @twoertwein 