proposition: Lemma last_holder'_locked_extend : forall tr h n, last_holder' h (tr ++ [(Client n, inr [Locked])]) = Some n.
proof: Proof. Proof using. induction tr; intros; simpl in *; repeat break_match; auto. Qed.
imports: Verdi(Verdi HandlerMonad) StructTact(Fin) Verdi(StatePacketPacketDecomposition)