val is_subset : comparator:('a, 'cmp) Base.Comparator.t ‑> ('a, 'cmp) named ‑> of_:('a, 'cmp) named ‑> unit Base.Or_error.t
val equal : comparator:('a, 'cmp) Base.Comparator.t ‑> ('a, 'cmp) named ‑> ('a, 'cmp) named ‑> unit Base.Or_error.t