anchor.diff:  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 ->
  
positive.code: %%--------------------------------------------------------------------
  -spec synchronize(file_meta:uuid(), fslogic_blocks:block(), boolean()) -> ok.
  synchronize(Uuid, Block = #file_block{size = RequestedSize}, Prefetch) ->
      ?info("SYNCHRONIZE ~p ~p", [Uuid, Block]),
      EnlargedBlock = Block#file_block{size = max(RequestedSize, ?MINIMAL_SYNC_REQUEST)},
      trigger_prefetching(Uuid, EnlargedBlock, Prefetch),
      {ok, Locations} = file_meta:get_locations({uuid, Uuid}),
  
negative.code: %%--------------------------------------------------------------------
  -spec notify_fun(any(), any(), any()) -> ok.
  notify_fun(Ref, Offset, Size) ->
      ok.
  
  %%--------------------------------------------------------------------
  %% @doc
  