val elements : t -> elt list
val mem : elt -> t -> bool
val iter : ( elt -> unit ) -> t -> unit
val fold : ( elt -> 'a -> 'a ) -> t -> 'a -> 'a
val filter : ( elt -> bool ) -> t -> t
val partition : ( elt -> bool ) -> t -> t * t
val for_all : ( elt -> bool ) -> t -> bool
val exists : ( elt -> bool ) -> t -> bool
val iter_sorted : ( elt -> unit ) -> t -> unit
val fold_sorted : ( elt -> 'a -> 'a ) -> t -> 'a -> 'a
val subset : t -> t -> bool
val intersect : t -> t -> bool
val of_list : elt list -> t