anchor.diff:      {binary_to_integer(Uid), binary_to_integer(Gid)}.
   
   %%%===================================================================
  -%%% API functions
  +%%% Internal functions
   %%%===================================================================
   
   %%--------------------------------------------------------------------
  
positive.code: %% storage helper is defined as insecure, storage admin context is returned.
  %% @end
  %%--------------------------------------------------------------------
  -spec get_client_user_ctx(od_user:id(), od_space:id(), storage:doc(), helpers:name()) ->
      {ok, user_ctx()} | {error, Reason :: term()}.
  get_client_user_ctx(UserId, SpaceId, StorageDoc, HelperName) ->
      case storage:select_helper(StorageDoc, HelperName) of
  
negative.code: %% respectively user ID and space ID. For the other storage returns 'undefined'.
  %% @end
  %%--------------------------------------------------------------------
  -spec generate_user_ctx(od_user:id(), od_space:id(), helper:name()) ->
      {ok, user_ctx()} | undefined.
  generate_user_ctx(?ROOT_USER_ID, _, ?POSIX_HELPER_NAME) ->
      {ok, #{<<"uid">> => <<"0">>, <<"gid">> => <<"0">>}};
  