anchor.diff:  file_request({advise,Offset,Length,Advise},
            #state{handle=Handle}=State) ->
       case ?PRIM_FILE:advise(Handle, Offset, Length, Advise) of
  -    {error,_}=Reply ->
  -        {stop,normal,Reply,State};
  +    {error,Reason}=Reply ->
  +        {stop,Reason,Reply,State};
       Reply ->
           {reply,Reply,State}
       end;
  
positive.code:     case unicode:characters_to_binary(Chars,InEncoding,OutEncoding) of
  	Bin when is_binary(Bin) ->
  	    case ?PRIM_FILE:write(Handle, Bin) of
  		{error,_}=Reply ->
  		    {stop,normal,Reply,NewState};
  		Reply ->
  		    {reply,Reply,NewState}
  	    end;
  	{error,_,_} ->
  	    {stop,normal,
  	     {error,{no_translation, InEncoding, OutEncoding}},
  	     NewState}
      end.
  
negative.code: file_request(truncate, 
  	     #state{handle=Handle}=State) ->
      case ?PRIM_FILE:truncate(Handle) of
  	{error,Reason}=Reply ->
  	    {stop,Reason,Reply,State#state{buf= <<>>}};
  	Reply ->
  	    std_reply(Reply, State)
      end;
  