Proof using.
intros.
solve_by_inversion' eauto.
Qed.

(* Specifications: *)
Lemma InputUnlock_held :
forall s c,
lb_step_execution lb_step_async s ->
held (nwState (evt_a (hd s)) (Client c)) = true ->
now (occurred (InputUnlock c)) s ->
next (fun s => In (mkPacket (Client c) Server Unlock) (nwPackets (evt_a (hd s)))) s.