∀ {α : Type u} {cmp : α → α → Ordering} {β : Type v} {t : Std.DTreeMap.Raw α (fun x => β) cmp} [Std.TransCmp cmp],
  t.WF → ∀ {a : α} (h' : a ∈ t), Std.DTreeMap.Raw.Const.get? t a = some (Std.DTreeMap.Raw.Const.get t a h')