{m : Type u → Type u} →
  {α : Type u} →
    {motive_1 : MLList.MLListImpl✝ m α → Sort u_1} →
      (t : MLList.MLListImpl✝¹ m α) → MLList.MLListImpl.ctorIdx✝ t = 0 → motive_1 MLList.MLListImpl.nil✝ → motive_1 t