∀ {α : Type u} {β : Type v} {cmp : α → α → Ordering} {t : Std.ExtTreeMap α β cmp} [inst : Std.TransCmp cmp]
  [inst_1 : Inhabited α], t ≠ ∅ → ∀ {k : α} {v : β}, (cmp t.maxKey! (t.insertIfNew k v).maxKey!).isLE = true