feat(data/nat/basic): add recursion principle `even_odd_rec` as a wrapper around `binary_rec` (#15457)
feat(data/nat/basic): add recursion principle `even_odd_rec` as a wrapper around `binary_rec` (#15457)

This is just a wrapper around `nat.binary_rec`, so that the subsequent reasoning after invoking this recursion principle can remain in the familiar world of `ℕ` and avoids having to switch to dealing with `bit0` and `bit1`.

Co-authored-by: Violeta Hernández <ef7791a37841fc4d43c525b2b4c85d848ab1cdf0@gmail.com>





leanprover-community/mathlib,leanprover-community/mathlib