{α : Sort u} →
  {β : Sort u_1} →
    {op : α → β → α} →
      {o : β} →
        {motive : Std.LawfulRightIdentity op o → Sort u_2} →
          ([toRightIdentity : Std.RightIdentity op o] → (right_id : ∀ (a : α), op a o = a) → motive ⋯) →
            (t : Std.LawfulRightIdentity op o) → motive t