anchor.diff:          helper_handle:create(SessId, UserId, SpaceId, StorageDoc),
   
       case session:add_local_links(SessId, ?HELPER_HANDLES_TREE_ID,
  -        link_key(StorageId, SpaceId), HandleId
  +        make_link_name(StorageId, SpaceId), HandleId
       ) of
           ok ->
               {ok, HelperHandle};
  
positive.code:     Result :: {ok, [HandleAndSpaceIds]} | {error, term()}.
  get_local_handles_by_storage(SessId, StorageId) ->
      FoldFun = fun(#link{name = Name, target = HandleId}, Acc) ->
          case decode_link_key(Name) of
              {StorageId, SpaceId} ->
                  {ok, [{HandleId, SpaceId} | Acc]};
              _ ->
  
negative.code: 
  -define(HELPER_HANDLES_TREE_ID, <<"helper_handles">>).
  
  % link name constructed from storage id and space id
  -type handle_link_name() :: datastore:link_name().
  
  %%%===================================================================
  %%% API
  %%%===================================================================
  