Section CalculatorApp.
Definition l1 := 1.
Definition l2 := 2.
Definition f args :=
match args with
| x::y::_ => Some (x + y)
| _ => None
end.
Definition prec (args : input) :=
if args is x::y::_ then true else false.
(* This server node *)
Definition sv : nid := 1.
Definition cl : nid := 2.
(* Delegate server *)
Definition sd := 3.

Lemma Hs2 : sd \in cs2. Proof. by []. Qed.