anchor.diff:      start_link/1,
       stop/1,
       send/3,
  -    send/5,
  +    reply/3,
  +    reply/4,
       subscribe/3,
       unsubscribe/3,
       subscribe_all/2,
  
positive.code: notify(_Subscriber, _Message, false) ->
      ok.
  
  do_send(Next, Sender, Destination, Payload) ->
      case is_routing_loop(Next, Sender) of
          false ->
  
negative.code: % TODO: Need type spec for Python/Ruby subscribers (ErlPort Pid and
  % function path)
  -type payload() :: term().
  -type topic() :: atom().
  % TODO: How to represent external functions?
  -type destination() :: [pid()].
  -type subscriber() :: pid().
  -type hub() :: erlport:server_instance().
  -type send_options() :: [route_by_path].
  -type message() :: #message{}.
  
  -define(IS_TOPIC(T), is_atom(T)).
  
  