{α : Type u_1} →
  (motive : List α → List α → Sort u_2) →
    (x x_1 : List α) →
      (Unit → motive [] []) →
        ((x : List α) → motive [] x) →
          ((x : List α) → motive x []) →
            ((x : α) → (xs : List α) → (y : α) → (ys : List α) → motive (x :: xs) (y :: ys)) → motive x x_1