    functor (Ord : OrderedType) ->
      sig
        type elt = Ord.t
        and t
        val empty : Set.S.t
        val is_empty : Set.S.t -> bool
        val mem : Set.S.elt -> Set.S.t -> bool
        val add : Set.S.elt -> Set.S.t -> Set.S.t
        val singleton : Set.S.elt -> Set.S.t
        val remove : Set.S.elt -> Set.S.t -> Set.S.t
        val union : Set.S.t -> Set.S.t -> Set.S.t
        val inter : Set.S.t -> Set.S.t -> Set.S.t
        val diff : Set.S.t -> Set.S.t -> Set.S.t
        val compare : Set.S.t -> Set.S.t -> int
        val equal : Set.S.t -> Set.S.t -> bool
        val subset : Set.S.t -> Set.S.t -> bool
        val iter : (Set.S.elt -> unit) -> Set.S.t -> unit
        val fold : (Set.S.elt -> 'a -> 'a) -> Set.S.t -> 'a -> 'a
        val for_all : (Set.S.elt -> bool) -> Set.S.t -> bool
        val exists : (Set.S.elt -> bool) -> Set.S.t -> bool
        val filter : (Set.S.elt -> bool) -> Set.S.t -> Set.S.t
        val partition : (Set.S.elt -> bool) -> Set.S.t -> Set.S.t * Set.S.t
        val cardinal : Set.S.t -> int
        val elements : Set.S.t -> Set.S.elt list
        val min_elt : Set.S.t -> Set.S.elt
        val max_elt : Set.S.t -> Set.S.elt
        val choose : Set.S.t -> Set.S.elt
      end