{α : Type u_1} →
  (motive : List α → List α → List α → Sort u_2) →
    (x x_1 x_2 : List α) →
      ((l₂ acc : List α) → motive [] l₂ acc) →
        ((l₁ acc : List α) → motive l₁ [] acc) →
          ((x : α) → (xs : List α) → (y : α) → (ys acc : List α) → motive (x :: xs) (y :: ys) acc) → motive x x_1 x_2