anchor.diff:  %%             [pid_groups:get_my(dht_node), self(), Case, {OldPidDHT, OldPidRT},
   %%              {NewPidDHT, NewPidRT}]).
   
  +-ifdef(GFRT).
  +
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % GFRT-chord
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   
  --ifdef(GFRT).
   % Additional information appended to an rt_entry()
   -record(rt_entry_info, {group = other_dc :: other_dc | same_dc}).
   -type rt_entry_info_t()::#rt_entry_info{}.
  
positive.code: set_adjacent_pred(#rt_entry{adjacent_fingers={_Pred, SuccId}} = Entry, PredId) ->
      set_adjacent_fingers(Entry, PredId, SuccId).
  
  -ifdef(GFRT).
  %% @doc Get the custom info field of a rt entry
  -spec get_custom_info(rt_entry()) -> custom_info().
  get_custom_info(#rt_entry{custom=CustomInfo}) -> CustomInfo.
  -endif.
  
  %% @doc Get the adjacent predecessor rt_entry() of the given node.
  -spec predecessor_node(RT::rt(), Node::rt_entry()) -> rt_entry().
  predecessor_node(RT, Node) ->
  
negative.code: rt_entry_info(_Node, _Type, _PredId, _SuccId) ->
      undefined.
  
  -endif.
  
  %% @doc Checks whether config parameters of the rt_frtchord/rt_gfrtchord
  %%      process exist and are valid.
  -spec frt_check_config() -> boolean().
  frt_check_config() -> true.
  