class mod_random ~kind ?replay_meta  mode children =
  let name ="quota" in
object
  inherit switch ~name ~kind ?replay_meta ~mode (List.map snd children)

  val mutable pos = 0
  val mutable play_list=[]
  (* Annihilate the reversal in #select once for all. *)
  val children = List.rev children

  method private select =

    let (ready_list,n) =

      (*
      fold_left função valor_inicial lista
      :: add na lista
        l é a lista vazia, k é 0
        Ao passar por aqui ela é revertida com a lista das filhas ficando em primeiro,peso em ultimo
      *)
      List.fold_left
        (fun (l,k) (w,s) -> if s.source#is_ready then (s,w)::l,(k+w) else l,k)
        ([],0) children
    in

      if n = 0 then None else
                    begin
                    let sel = pos+1 in
                    pos <- sel ;
                     print_string("AKI "^string_of_int(pos)^"%!");
                    let (play_list,pos)=List.fold_left (fun (l,n) (s,w) -> if n mod w=0 then
                                     (s::l,n)
                            else if (List.length(l))<=0 then(l,n+1)
                            else(l,n))
                        ([],sel) ready_list in

                 let retval=List.hd(play_list) in
                 play_list<-List.tl(play_list);

                    Some  retval
                end;
  method stype =
    if List.exists (fun (_,s) -> s.source#stype = Infallible) children then
      Infallible
    else
      Fallible
end