anchor.diff:           passed_state            = ?required(state, passed_state)
                                          :: none | passed_state(),
            num_possible_executions = ?required(state, passed_state)
  -                                       :: pos_integer()
  +                                       :: pos_integer(),
  +         callback_on_deliver     = ?required(state, callback_on_deliver)
  +                                       :: callback_on_deliver()
           }).
   
   -type state_t() :: #state{}.
  +
   -spec start() -> ok.
   start() -> start(default).
   
  
positive.code:     %% stop sending epidemic messages
      erlang:erase(trace_mpath),
      ok.
  
  -spec get_infos() -> [tuple()].
  get_infos() -> get_infos(default).
  
negative.code: -export([start/0, start/1, start/2, stop/0]).
  -export([start_deliver/0, start_deliver/1]).
  -export([get_infos/0, get_infos/1]).
  -export([register_callback/1, register_callback/2]).
  -export([cleanup/0, cleanup/1]).
  
  %% report messages from other modules
  