Instance CompSpecs : compspecs.Definition Vprog : varspecs.Instance LS: listspec _list _tail (fun _ _ => emp).Definition t_struct_list := Tstruct _list noattr.

(* Specifications: *)
Lemma is_pointer_or_null_not_null: forall x, is_pointer_or_null x -> x <> nullval -> isptr x.
Lemma body_append: semax_body Vprog Gprog f_append append_spec.