∀ {α : Type u} {β : Type v} {cmp : α → α → Ordering} {t : Std.TreeMap α β cmp} [Std.TransCmp cmp] [inst : BEq α]
  [Std.LawfulBEqCmp cmp] {l : List (α × β)} {k k' : α},
  cmp k k' = Ordering.eq →
    ∀ {v : β}, List.Pairwise (fun a b => ¬cmp a.1 b.1 = Ordering.eq) l → (k, v) ∈ l → (t.insertMany l)[k']? = some v