anchor.diff:  -spec external_rt_get_tree(RT :: external_rt()) -> gb_tree().
   external_rt_get_tree(RT) when is_tuple(RT) ->
       element(2, RT).
  +
  +% @doc Get the size of the external rt
  +-spec external_rt_get_size(RT :: external_rt()) -> non_neg_integer().
  +external_rt_get_size(RT) ->
  +    gb_trees:size(external_rt_get_tree(RT)).
   
   %% Get the node with the given Id. This function will crash if the node doesn't exist.
   -spec rt_get_node(NodeId :: key(), RT :: rt()) -> rt_entry().
  
positive.code: %% @doc Returns the size of the routing table.
  -spec get_size(rt() | external_rt()) -> non_neg_integer().
  get_size(#rt_t{} = RT) -> gb_trees:size(get_rt_tree(RT));
  get_size(RT) -> external_rt_get_ring_size(RT). % size of external rt
  %% userdevguide-end rt_frtchord:get_size
  
  %% userdevguide-begin rt_frtchord:n
  
negative.code: rt_set_nodes(#rt_t{} = RT, Nodes) -> RT#rt_t{nodes=Nodes}.
  
  % @doc Set the size estimate of the ring
  -spec rt_set_ring_size(RT :: rt_t(), Size :: unknown | gossip_state:size()) -> rt_t().
  rt_set_ring_size(RT, Size) -> RT#rt_t{nodes_in_ring=Size}.
  
  % @doc Get the ring size estimate from the external routing table
  