Wrapper around Set
type 'a iter = ('a -> unit) -> unit
type 'a printer = Stdlib.Format.formatter -> 'a -> unit
module type OrderedType = Stdlib.Set.OrderedType
module type S = sig ... end
module Make (O : Stdlib.Set.OrderedType) : S with type t = Stdlib.Set.Make(O).t and type elt = O.t