Sort u_1 →
  {α : Type u} →
    {β : α → Type v} →
      {cmp : α → α → Ordering} →
        Std.ExtDTreeMap α β cmp →
          {α' : Type u} → {β' : α' → Type v} → {cmp' : α' → α' → Ordering} → Std.ExtDTreeMap α' β' cmp' → Sort u_1