Definition client_step (this to : nid) (d : dstatelet)
           (msg : seq nat)
           (pf : client_send_safe this to d msg) :=
  Some Heap.empty.

(* Specifications: *)
Lemma client_step_coh : s_step_coh_t coh the_tag client_step.
Lemma client_step_def this to d msg : client_send_safe this to d msg <-> exists b pf, @client_step this to d msg pf = Some b.