val trace : ?msg:string -> int -> int -> StateSet.t -> StateSet.t  -> unit
(** [trace nid round d t msg] records a the message [msg] together with the a node preorder
    [nid], the [round], the [d]one set and the [t]odo set *)
val finalize_node : int -> int -> bool -> unit
val gen_trace : Ata.t -> (module Tree.S with type t = 'a) -> 'a -> unit