Goal:
    A : Type  B : Type  f : A → B
  ============================
   (∀ n : nat,
      (∀ l : list A, nth_error (map f l) n = option_map f (nth_error l n))
      → ∀ l : list A,
          nth_error (map f l) (S n) = option_map f (nth_error l (S n)))


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