let get_result env =
match env.result,env.return with
| Some x,Some t -> x, t
| Some _, _ -> Wp_parameters.fatal "Result type undefined"
| None,_ ->
match env.return with
| Some typ ->
let x = D.fresh "result" (Mdata.Vacsl(Ctype typ)) in
env.result <- Some x ; (x, typ)
| None ->
Wp_parameters.fatal "Result type undefined"