(n : ℕ) →
  (motive : Option (Vector (Option (Fin n)) n) → Sort u_1) →
    (x : Option (Vector (Option (Fin n)) n)) →
      ((map : Vector (Option (Fin n)) n) → motive (some map)) →
        ((x : Option (Vector (Option (Fin n)) n)) → motive x) → motive x