val copy_into : into:t -> t -> unit
val insert : t -> elt -> unit
val remove : t -> elt -> unit
val mem : t -> elt -> bool
val inter_mut : into:t -> t -> unit
val union_mut : into:t -> t -> unit
val subset : t -> t -> bool
val equal : t -> t -> bool
val for_all : (elt -> bool) -> t -> bool
val exists : (elt -> bool) -> t -> bool
val iter : (elt -> unit) -> t -> unit
val fold : ('a -> elt -> 'a) -> 'a -> t -> 'a
val elements : t -> elt list
val of_list : elt list -> t