∀ {α : Type u} {β : Type v} {cmp : α → α → Ordering} [inst : Std.TransCmp cmp] (t t_1 : Std.ExtTreeMap α β cmp),
  t = t_1 →
    ∀ (a a_1 : α), a = a_1 → ∀ (b b_1 : β), b = b_1 → t.getThenInsertIfNew? a b = t_1.getThenInsertIfNew? a_1 b_1