∀ {α : Type u_1} (motive : Ordnode α → α → Ordnode α → Sort u_2) (l : Ordnode α) (x : α)
  (h_1 :
    (l : Ordnode α) →
      (x : α) → (size : ℕ) → (m : Ordnode α) → (y : α) → (r : Ordnode α) → motive l x (Ordnode.node size m y r))
  (h_2 : (l : Ordnode α) → (x : α) → motive l x Ordnode.nil),
  (match l, x, Ordnode.nil with
    | l, x, Ordnode.node size m y r => h_1 l x size m y r
    | l, x, Ordnode.nil => h_2 l x) =
    h_2 l x