Proof with auto.
intros H0 H1 H2. unfold do_unfold'.
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding1_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding2_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding3_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding4_sound;auto].
rewrite listd_app, listd_unfold_state; split. solve[apply unfolding6_sound;auto].
auto.
Qed.

Lemma add_list_to_set_spec2:
forall l s, add_list_to_set l s = None ->
Forall (fun x => M.In x s) l.