fact: Definition fix0 (B : Type) : (gtactic B -> gtactic B) -> gtactic B := @M.fix1 (goal _) (fun _ => mlist (B *m (goal _))).
imports: Strings.String ssrmatching.ssrmatching Mtac2(Logic Datatypes List Utils Logic intf.Sorts) Strings.String NArith.BinNat NArith.BinNatDef