fact: Definition rewrite {X : Type} (C : X -> Type) {a b : X} (H : a = b) : ttac (C b) -> ttac (C a) := fun t => '(m: x, gs) <- t; M.ret (m: match H in _ = z return (C z) -> (C a) with | eq_refl => fun x => x end x, gs).
imports: Mtac2(Base Datatypes List Sorts tactics.Tactics) Strings.String Strings.String