(* The next line is "boilerplate", always required after importing an AST. *)
Instance CompSpecs : compspecs. make_compspecs prog. Defined.
Definition Vprog : varspecs.  mk_varspecs prog. Defined.
(* Functional spec of this program.  *)
Definition sum_Z : list Z -> Z := fold_right Z.add 0.

Lemma sum_Z_app:
forall a b, sum_Z (a++b) =  sum_Z a + sum_Z b.