Small documentation/comment fixes in context.py

Description

While working on !1045 (merged), I noticed some documentation errors in context.py.

I did originally have these fixes within !1045 (merged)'s commit series, but I've split them out because:

1. They're irrelevant to that commit series.
2. !1045 (merged) is large enough, irrelevant commits are not going to help whoever is reviewing it.