c235e5055fmusig-spec: Add naive Python reference implementation (Elliott Jin) Pull request description: ACKs for top commit: jonasnick: ACKc235e5055freal-or-random: utACKc235e5055fTree-SHA512: f0ff8b84730a82d8eab15ac5c46b190af125a87c0c8b3eef88fa5f67c4b7cd88e3d981cae857a99456b72a0edb56ef7f0593e7ed488914f2f4cd070efb579de8