∀ {α : Type u} {β : α → Type v} [inst : Ord α] [Std.TransOrd α] [instBEq : BEq α] [Std.LawfulBEqOrd α] {k : α}
  {t : Std.DTreeMap.Internal.Impl α β}, t.Ordered → t.getKey? k = Std.Internal.List.getKey? k t.toListModel