anchor.diff:   {env with scope_mods = scope_mod :: env.scope_mods}
   
   let try_lookup_id (env:env) (x:id): (typ * id_info option) option = 
  -  match lookup_name env x with
  +  match lookup_name env x true with
     | (Some (Info (t, info)), _) -> Some (t, info)
     | (Some (Name x), _) -> unsupported ("unsupported '" + (err_id x) + "'")
     | _ -> None
  
positive.code:   match id with
    | Reserved _ -> ()
    | _ ->
      match lookup_name env id with
      | (None, _) -> err ("Identifier not found " + (err_id id))
      | (Some r, _) -> ()
  
  
negative.code:   | _ -> None
  
  let check_not_local env x = 
    match lookup_name env x false with
    | (Some (Info (t, info)), _) -> err ("formal: " + (err_id x) + " is a local variable")
    | _ -> ()
  
  