Goal:
    A : Type  B : Type  f : nat → A → B  l : list A
  ============================
   (List.rev (mapi_rec f l (0 - 0)) =
    mapi_rec (λ (k : nat) (x : A), f (Nat.pred #|l| - k) x) (List.rev l) 0)


DEBUG:Going to execute:
rewrite rev_mapi_rec
DEBUG LTAC Evaluated term: 0
DEBUG LTAC Evaluated term: (0 - 0)