anchor.diff:  
   read_fun(Expected) ->
       fun(_Handle, _Offset, _Size) ->
  +        ?info_stacktrace("DEBUG READ_FUN~n"),
           Expected
       end.
   
   write_fun(Expected) ->
       fun(_Handle, _Offset, _Data) ->
  +        ?info_stacktrace("DEBUG WRITE_FUN~n"),
           Expected
       end.
   
   open_fun(Expected) ->
  -    fun(_UUID, _Mode) -> Expected end.
  +    fun(_UUID, _Mode) -> ?info_stacktrace("DEBUG OPEN_FUN~n"),Expected end.
   
   close_fun() ->
  -    fun(_Handle) -> ok end.
  -
  -notify_fun() -> fun(_Ref, _Offset,_Size) -> ok end.
  +    fun(_Handle) -> ?info_stacktrace("CLOSE_FUN~n"),ok end.
  +
  +notify_fun() ->
  +    fun(_Ref, _Offset,_Size) ->
  +        ?info_stacktrace("DEBUG NOTIFY_FUN~n"),
  +        ok
  +    end.
   
   notify_fun(CounterPid) ->
       fun(_Ref, _Offset,_Size) ->
  +        ?info_stacktrace("DEBUG NOTIFY_FUN, counterpid = ~p~n", [CounterPid]),
           CounterPid ! increase,
           ok
       end.
   
   on_complete_fun(Pid) ->
       fun(_Ref, Arg) ->
  +        ?info_stacktrace("DEBUG ON_COMPLETE_FUN: ~p, pid = ~p~n", [Arg, Pid]),
           Pid ! {on_complete, Arg},
           ok
       end.
  
positive.code: 
  init_per_suite(Config) ->
      Config.
  %%     ?TEST_INIT(Config, ?TEST_FILE(Config, "env_desc.json")).
  
  end_per_suite(_Config) ->
      ok.
  %%     test_node_starter:clean_environment(_Config).
  
  
  init_per_testcase(_, Config) ->
      NewConfig = ?TEST_INIT(Config, ?TEST_FILE(Config, "env_desc.json")),
  
negative.code:         )
      ),
  
      Ref1 = remote_apply(
          Worker1, rtransfer, prepare_request,
          [Worker2, ?TEST_FILE_UUID, Offset, DataSize]
      ),
  
      ?assertMatch({error, _},
  