anchor.diff:          <<Id/binary>> ->
               store(cluster_id, Id, Service);
           Error ->
  -            fetch(cluster_id, Service, Error)
  +            fetch_or_throw(cluster_id, Service, Error)
       end;
   
   get_id(Service = oneprovider) ->
  
positive.code: %% Throws given Error on failure.
  %% @end
  %%--------------------------------------------------------------------
  -spec fetch(Key :: term(), Service :: service:name(), ErrorResult :: term()) ->
      FoundValue :: term().
  fetch(Key, Service, Error) ->
      case service:get_ctx(Service) of
          #{Key := Value} -> Value;
          _ -> throw(Error)
  
negative.code:         #{cluster := <<Id/binary>>} ->
              store(cluster_id, Id, Service)
      catch _Type:Error ->
          fetch_or_throw(cluster_id, Service, ?make_stacktrace(Error))
      end.
  
  
  