Hello,
I have created a ticket on Trac that links to the code on my github, which is ready for a code review. This includes both TorExport (stem/descriptor/export.py) which has already received a quick review and the unit tests (test/unit/descriptor/export.py).
The ticket (#6512) can be found at https://trac.torproject.org/projects/tor/ticket/6512.
-Erik & Megan