Goal:
    A : Type  B : Type  f : A → B  l : list A
  ============================
   ((fix aux (l : list A) (acc : list B) {struct l} : list B :=
       match l with
       | [] => acc
       | x :: l0 => aux l0 (f x :: acc)
       end) l [] = List.rev (map f l))


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrrewrite@0> $1 $2