anchor.diff:  ;;;| boolean is_a (in string logical_type_id);
   ;;; _is_a in lisp mapping (in clorb-request)
   
  +(define-method _is_a ((obj t) interface-id)
  +  (declare (ignore interface-id))
  +  (error 'corba:no_implement :minor 3))
  +
   (define-method _is_a ((obj CORBA:Object) interface-id)
     (object-is-a obj interface-id))
   
  
positive.code: 
  ;;;| boolean	non_existent();
  ;;; _non_existent in lisp mapping
  
  (define-method _non_existent ((obj CORBA:Proxy))
    ;;FIXME: Should perhaps send a "_non_existent" message to object ?
  
negative.code: ;;;|     inout NamedValue result,				
  ;;;|     out Request	request,		
  ;;;|     in Flags        req_flags    );
  
  (define-method _create_request ((obj t) ctx operation arg_list result req_flags)
    (declare (ignore ctx operation arg_list result req_flags))
    (error 'CORBA:NO_IMPLEMENT :minor 4))
  
  
  (define-method _create_request ((obj CORBA:Object)
                                  ctx operation arg_list result req_flags)
  