let creer_file () = [],[];;

let enfiler_file (t,q) x = (t, x::q);;

let rec defiler_file = function
  | [], [] -> failwith "Empty queue"
  | x::tq, q -> x, (tq, q)
  | [], q -> defiler_file (List.rev q, [])
;;

let est_vide_file = function
  | [], [] -> true
  | _ -> false
;;