∀ {α : Type u} {cmp : α → α → Ordering} [inst : Std.TransCmp cmp] [inst_1 : Inhabited α] {l : List α} {k k' : α},
  cmp k k' = Ordering.eq →
    List.Pairwise (fun a b => ¬cmp a b = Ordering.eq) l → k ∈ l → (Std.ExtTreeMap.unitOfList l cmp).getKey! k' = k