anchor.diff:  %%% API
   %%%===================================================================
   
  -union(PrivilegesA, PrivilegesB) ->
  -    ordsets:union(
  -        ordsets:from_list(PrivilegesA),
  -        ordsets:from_list(PrivilegesB)
  -    ).
  -
  -
  -proplists_union(PrivilegesProplist) ->
  -    PrivilegesMap = lists:foldl(
  -        fun({Id, Privs}, AccMap) ->
  -            NewPrivs = case maps:get(Id, AccMap, undefined) of
  -                undefined ->
  -                    ordsets:from_list(Privs);
  -                OtherPrivs ->
  -                    union(Privs, OtherPrivs)
  -            end,
  -            maps:put(Id, NewPrivs, AccMap)
  -        end, #{}, PrivilegesProplist),
  -    ordsets:from_list(maps:to_list(PrivilegesMap)).
  -
  -
   %%--------------------------------------------------------------------
   %% @doc A privilege level of a Space user.
   %%--------------------------------------------------------------------
   -spec space_user() -> [space_privilege()].
   space_user() ->
  -    [space_view_data, space_write_files].
  +    ordsets:from_list([space_view_data, space_write_files]).
   
   %%--------------------------------------------------------------------
   %% @doc A privilege level of a Space manager.
  
positive.code:     oz_privilege/0
  ]).
  
  -export([union/2, proplists_union/1]).
  
  -export([space_user/0, space_manager/0, space_admin/0, space_privileges/0]).
  -export([group_user/0, group_manager/0, group_admin/0, group_privileges/0]).
  -export([handle_service_user/0, handle_service_admin/0,
  
negative.code: %% @doc All view privileges in OZ API.
  %%--------------------------------------------------------------------
  -spec oz_viewer() -> [oz_privilege()].
  oz_viewer() ->
      ordsets:from_list([
          list_users,
  
          list_groups,
  
          list_spaces,
          list_providers_of_space,
  
          list_providers,
          list_users_of_provider,
          list_groups_of_provider,
          list_spaces_of_provider
      ]).
  
  
  %%--------------------------------------------------------------------
  