∀ {α : Type u_1} (motive : (x : Ordnode α) → x.Sized → Prop) (x : Ordnode α) (x_1 : x.Sized),
  (∀ (x : Ordnode.nil.Sized), motive Ordnode.nil x) →
    (∀ (l : Ordnode α) (x : α) (r : Ordnode α) (sl : l.Sized) (sr : r.Sized),
        motive (Ordnode.node (l.size + r.size + 1) l x r) ⋯) →
      motive x x_1