anchor.diff:  %%--------------------------------------------------------------------
   %% @doc All view privileges in OZ API.
   %%--------------------------------------------------------------------
  --spec oz_viewer() -> [oz_privilege()].
  +-spec oz_viewer() -> privileges(oz_privilege()).
   oz_viewer() ->
  -    ordsets:from_list([
  +    from_list([
           list_users,
   
           list_groups,
  
positive.code: %%--------------------------------------------------------------------
  %% @doc A privilege level of a group user.
  %%--------------------------------------------------------------------
  -spec group_user() -> [group_privilege()].
  group_user() ->
      [group_view_data].
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a group manager.
  %%--------------------------------------------------------------------
  -spec group_manager() -> [group_privilege()].
  group_manager() ->
      ordsets:union(
          group_user(),
          ordsets:from_list([
              group_invite_user,
              group_remove_user,
              group_invite_group,
              group_remove_group
          ])
      ).
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a group administrator. This level contains all
  %% atoms representing group privileges.
  %% @end
  %%--------------------------------------------------------------------
  -spec group_admin() -> [group_privilege()].
  group_admin() ->
      ordsets:union(
          group_manager(),
          ordsets:from_list([
              group_create_space,
              group_create_space_token,
              group_join_space,
              group_leave_space,
              group_set_privileges,
              group_change_data,
              group_remove,
              group_join_group
          ])
      ).
  
  %%--------------------------------------------------------------------
  %% @doc All atoms representing group privileges.
  %% @equiv group_admin()
  %%--------------------------------------------------------------------
  -spec group_privileges() -> [group_privilege()].
  group_privileges() ->
      group_admin().
  
  
negative.code: %%--------------------------------------------------------------------
  %% @doc A privilege level of a handle_service user.
  %%--------------------------------------------------------------------
  -spec handle_service_user() -> privileges(handle_service_privilege()).
  handle_service_user() ->
      from_list([view_handle_service, register_handle]).
  
  %%--------------------------------------------------------------------
  %% @doc A privilege level of a handle_service administrator. This level contains all
  %% atoms representing handle_service privileges.
  %% @end
  %%--------------------------------------------------------------------
  -spec handle_service_admin() -> privileges(handle_service_privilege()).
  handle_service_admin() ->
      union(handle_service_user(), [
  %%        register_handle_service, % we may need those privileges for admins in oz_privileges
  %%        list_handle_services,
          delete_handle_service,
          modify_handle_service,
          view_handle_service
      ]).
  
  %%--------------------------------------------------------------------
  %% @doc All atoms representing handle_service privileges.
  %% @equiv handle_service_admin()
  %%--------------------------------------------------------------------
  -spec handle_service_privileges() -> privileges(handle_service_privilege()).
  handle_service_privileges() ->
      handle_service_admin().
  
  