fact: Definition symmetry_in {T} {x y: T} (H: x = y) : tactic := apply_in (@Coq.Init.Logic.eq_sym _ _ _) H.
imports: Strings.String ssrmatching.ssrmatching Mtac2(Logic Datatypes List Utils Logic Sorts MTeleMatch) Strings.String NArith.BinNat NArith.BinNatDef