module type SA =
  sig
    type data
    type t 
    val make : data -> t
    val node : t -> data
    val hash : t -> int
    val uid : t -> int
    val equal : t -> t -> bool
  end

module type S =
  sig
    type data
    type t = private { id : int;
		       key : int;
		       node : data }
    val make : data -> t
    val node : t -> data
    val hash : t -> int
    val uid : t -> int
    val equal : t -> t -> bool
  end

module Make (H : Hashtbl.HashedType) : S with type data = H.t