Ltac NoLabelTac :=
  match goal with
  | [ |- nolabel_list nil ] => exact I
  | [ |- nolabel_list (final _ _) ] => apply nolabel_final (*; NoLabelTac*)
  | [ |- nolabel_list (_ :: _) ] => simpl; split; NoLabelTac
  | [ |- nolabel_list (_ ++ _) ] => apply nolabel_list_app; NoLabelTac
  | [ H: _ -> nolabel_list ?x |- nolabel_list ?x ] => apply H; NoLabelTac
  | [ |- nolabel (makeseq _) ] => apply makeseq_nolabel; NoLabelTac
  | [ |- nolabel (makeif _ _ _) ] => apply makeif_nolabel; NoLabelTac
  | [ |- nolabel (make_set _ _) ] => apply make_set_nolabel
  | [ |- nolabel (make_assign _ _) ] => apply make_assign_nolabel
  | [ |- nolabel _ ] => red; intros; simpl; auto
  | [ |- _ /\ _ ] => split; NoLabelTac
  | _ => auto
  end.

Lemma tr_find_label_expression: forall r s a, tr_expression r s a -> forall k, find_label lbl s k = None.