anchor.diff:  %%--------------------------------------------------------------------
   -spec notify_fun(any(), any(), any()) -> ok.
   notify_fun(Ref, Offset, Size) ->
  -    ?info("NOTIFY ~p ~p ~p", [Ref, Offset, Size]).
  -
  +    ok.
   
   %%--------------------------------------------------------------------
   %% @doc
  
positive.code: prefetch_data_fun(FileUuid, #file_block{offset = O, size = S}) ->
      fun() ->
          try
              ?info("PREFETCH ~p ~p", [FileUuid, #file_block{offset = O + S, size = ?PREFETCH_SIZE - S}]),
              replica_synchronizer:synchronize(FileUuid, #file_block{offset = O + S, size = ?PREFETCH_SIZE - S}, false)
          catch
              _:Error ->
  
negative.code: %%--------------------------------------------------------------------
  -spec synchronize(file_meta:uuid(), fslogic_blocks:block(), boolean()) -> ok.
  synchronize(Uuid, Block = #file_block{size = RequestedSize}, Prefetch) ->
      EnlargedBlock = Block#file_block{size = max(RequestedSize, ?MINIMAL_SYNC_REQUEST)},
      trigger_prefetching(Uuid, EnlargedBlock, Prefetch),
      {ok, Locations} = file_meta:get_locations({uuid, Uuid}),
  