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