Proof using.
unfold message_enables_label, enabled.
intros.
find_apply_lem_hyp in_split.
break_exists_name xs. break_exists_name ys.
do 2 eexists.
eapply LabeledStepAsync_deliver; eauto.
simpl. monad_unfold. simpl. eauto.
Qed.

Lemma Locked_delivered_MsgLocked :
forall i, message_delivered_label
{| pSrc := Server; pDst := Client i; pBody := Locked |}
(MsgLocked i).