∀ {α : Type u} {β : α → Type v} {cmp : α → α → Ordering} {t : Std.DTreeMap.Raw α β cmp} [Std.TransCmp cmp]
  [inst : Std.LawfulEqCmp cmp],
  t.WF →
    ∀ {k a : α} [inst_1 : Inhabited (β a)], (t.erase k).get! a = if cmp k a = Ordering.eq then default else t.get! a