anchor.diff:  -spec delete_helpers_on_this_node(SessId :: id()) ->
       ok | datastore:generic_error().
   delete_helpers_on_this_node(SessId) ->
  -    model:execute_with_default_context(?MODULE, foreach_link,
  +    Links = model:execute_with_default_context(?MODULE, foreach_link,
           [SessId, fun
  -            (_LinkName, {_V, [{_, _, HelperKey, helper_handle}]}, _) ->
  -                helper_handle:delete(HelperKey);
  -            (_, _, _) ->
  -                ok
  -        end, undefined],
  +            (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.
   
  
positive.code:             end);
  
          {{error, link_not_found}, true} ->
              add_missing_helper(SessionId, SpaceId, StorageDoc);
  
          {{error, Reason}, _} ->
  
negative.code: 
      case model:execute_with_default_context(
          ?MODULE, add_links,
          [SessionId, [{link_key(StorageId, SpaceId), {Key, helper_handle}}]],
          [{level, ?HELPER_LINK_LEVEL}]
      ) of
          ok ->
  