anchor.diff:  -spec schedule_timer() -> reference().
   schedule_timer() ->
       erlang:send_after(1000, self(), timeout).
  +
  +-spec maybe_create_status_file(binary()) -> ok.
  +maybe_create_status_file(Status) ->
  +    case application:get_env(amoc, status_file) of
  +        undefined ->
  +            ok;
  +        {ok, StatusFile} ->
  +            ok = file:write_file(StatusFile, Status)
  +    end.
  
positive.code: %% ------------------------------------------------------------------
  -spec handle_start(string(), file:filename(), state()) -> state().
  handle_start(Host, Directory, #state{to_ack=Ack}=State) ->
      _Port = start_slave_node(Host, Directory),
      Node = node_name(Host),
      Ack1 = [{Node, ?DEFAULT_RETRIES} | Ack],
  
negative.code: ping_slave_nodes(#state{to_ack=Ack}=State) ->
      Ack1 = lists:filtermap(fun ping_slave_node/1, Ack),
      case Ack1 of
          []  -> maybe_create_status_file(<<"ready">>);
          _   -> schedule_timer()
      end,
      State#state{to_ack=Ack1}.
  