Got a few options here:
* Implement an #ActivityPub / #ActivityStreams library from scratch. I did this lightly in C++ for ActivityDesk.
* Extract logic that'd go stale from @pleromafeed - bad idea since that'll get out of sync fast
* Work to refactor bits of logic from Pleroma - now I'd have to work on Pleroma code and this library to keep them in sync.
* Forgo #ActivityPub altogether and look into using http://fed.brid.gy/