{α : Type u_1} →
  (motive : WithTop α → ℕ → Sort u_2) →
    (a : WithTop α) →
      (n : ℕ) →
        ((a : α) → (n : ℕ) → motive (some a) n) → (Unit → motive none 0) → ((_n : ℕ) → motive none _n.succ) → motive a n