∀ (motive : String.Legacy.Iterator → ℕ → Sort u_1) (it : String.Legacy.Iterator) (n : ℕ)
  (h_1 : (it : String.Legacy.Iterator) → motive it 0)
  (h_2 : (it : String.Legacy.Iterator) → (n : ℕ) → motive it n.succ),
  (match it, n.succ with
    | it, 0 => h_1 it
    | it, n.succ => h_2 it n) =
    h_2 it n