Definition greet_tag := 0.

(* Specifications: *)
(* We might need to put this statement into a separate definition *)
Lemma greet_step_coh this to d msg (pf : greet_safe this to d msg) b :
let: f := dstate d in
let: s := dsoup d  in
Some b = greet_step pf ->
let: f' := upd this b f in
let: tms := TMsg greet_tag msg in
let: s' := (post_msg s (Msg tms this to true)).1 in
coh (DStatelet f' s').