anchor.diff:  fetch_lock_fetch_helper(SessionId, SpaceId, StorageDoc, InCriticalSection) ->
       StorageId = storage:get_id(StorageDoc),
       FetchResult = model:execute_with_default_context(
  -        ?MODULE, fetch_link_target, [SessionId, link_key(SpaceId, StorageId)],
  +        ?MODULE, fetch_link_target, [SessionId, link_key(StorageId, SpaceId)],
           [{level, ?HELPER_LINK_LEVEL}]
       ),
   
  
positive.code: 
      case model:execute_with_default_context(
          ?MODULE, add_links,
          [SessionId, [{link_key(SpaceId, StorageId), {Key, helper_handle}}]],
          [{level, ?HELPER_LINK_LEVEL}]
      ) of
          ok ->
  
negative.code: -spec delete_helpers_on_this_node(SessId :: id()) ->
      ok | datastore:generic_error().
  delete_helpers_on_this_node(SessId) ->
      Links = model:execute_with_default_context(?MODULE, foreach_link,
          [SessId, fun
              (LinkName, {_V, [{_, _, HelperKey, helper_handle}]}, Acc) ->
                  helper_handle:delete(HelperKey),
                  [LinkName | Acc];
              (_, _, Acc) ->
                  Acc
          end, []],
          [{level, ?HELPER_LINK_LEVEL}]
      ),
      model:execute_with_default_context(
          ?MODULE, delete_links, [SessId, Links]
      ),
      ok.
  
  