anchor.diff:  %%--------------------------------------------------------------------
   -spec user_root_dir_uuid(UserId :: od_user:id()) -> file_meta:uuid().
   user_root_dir_uuid(UserId) ->
  -    <<"userRoot", "_", UserId/binary>>.
  +    <<?USER_ROOT_PREFIX, UserId/binary>>.
   
   %%--------------------------------------------------------------------
   %% @doc Returns Uuid of user's root directory.
  
positive.code: -spec space_dir_uuid_to_spaceid_no_error(file_meta:uuid()) -> od_space:id().
  space_dir_uuid_to_spaceid_no_error(SpaceUuid) ->
      case SpaceUuid of
          <<"space", "_", SpaceId/binary>> ->
              SpaceId;
          _ ->
              <<>>
  
negative.code: -spec space_dir_uuid_to_spaceid(file_meta:uuid()) -> od_space:id().
  space_dir_uuid_to_spaceid(SpaceUuid) ->
      case SpaceUuid of
          <<?SPACE_ROOT_PREFIX, SpaceId/binary>> ->
              SpaceId;
          _ ->
              throw({not_a_space, {uuid, SpaceUuid}}) %todo remove this throw and return undefined instead
  