anchor.diff:  
   
   handle2(_ProtocolVersion, {register_hook, Fun}) ->
  +    ct:print("REG2"),
       dbsync_hooks:register(Fun);
   
   handle2(_ProtocolVersion, {remove_hook, HookId}) ->
  
positive.code:                     end;
                  _ -> ok
              end;
          (_, _, _, _) -> ok
      end,
  
      {ok, Delay} = application:get_env(?APP_Name, dbsync_hook_registering_delay),
  
negative.code: 
  register_available_blocks_hook() ->
      % register hook for #available_blocks docs
      ct:print("REG1"),
      MyProviderId = cluster_manager_lib:get_provider_id(),
      HookFun = fun
          (?FILES_DB_NAME, _, Uuid, #db_document{record = #available_blocks{provider_id = Id, file_id = FileId}}) when Id =/= MyProviderId ->
              ct:print("FOUND1"),
              {ok, Docs} = dao_lib:apply(dao_vfs, available_blocks_by_file_id, [FileId], 1),
              MyDocs = lists:filter(
                  fun(#db_document{record = #available_blocks{provider_id = Id}}) -> Id == MyProviderId end, Docs),
  