KnownBits in Lean

In January I was at the excellent E-Graphs Dagstuhl where I met some really amazing people. One of the things I did during that week was to talk to Marcus Rossel and Andrés Goens about proving the soundness of Knownbits transfer functions in Lean . I don't really know any Lean, so it was really useful to have two people that know a lot about it to hold my hand through my attempts. Thanks a lot,…