functor (Pre : PREFIX) ->
functor (Obs : OBSERVER) ->
functor (Img : IMG) ->
functor (State : sig type obs = Obs.t val add_wl : obs -> unit end) ->
sig
type obs = Obs.t
type t
val create : unit -> t
val compare : t -> t -> int
val total_ord : t -> t -> int
val add_alias : t -> t -> unit
val do_normalize : t -> unit
val add_observer : obs -> t -> unit
val remove_observer : obs -> t -> unit
val string_of : t -> string
val reset : unit -> unit
val get_all_ts : unit -> t list
type img = Img.t
val add_img : img -> t -> unit
val get_img : t -> img option
end