anchor.diff:                                 {error, _} = ERROR ->
                                      ERROR
                              end
  +                   end},
  +         #{desc => "(maybe) unlink socket",
  +           cmd  => fun(#{domain   := local,
  +                         local_sa := #{path := Path}} = State) ->
  +                           case os:cmd("unlink " ++ Path) of
  +                               "" ->
  +                                   ?SEV_IPRINT("path unlinked: "
  +                                               "~n   Path: ~s", [Path]),
  +                                   {ok, maps:remove(local_sa, State)};
  +                               Result ->
  +                                   ?SEV_EPRINT("unlink maybe failed: "
  +                                               "~n   Path: ~s"
  +                                               "~n   Res:  ~s",
  +                                               [Path, Result]),
  +                                   ok
  +                           end;
  +                      (_) ->
  +                           ok
                      end},
            #{desc => "announce ready (close)",
              cmd  => fun(#{tester := Tester} = _State) ->
  
positive.code:     ?SEV_IPRINT("await terminate"),
      Reason = tpp_udp_handler_await_terminate(Parent),
      ?SEV_IPRINT("terminate with ~p", [Reason]),
      tpp_udp_sock_close(Sock),
      ?SEV_IPRINT("terminating"),
      exit(Reason).
  
  
negative.code: tpp_udp_client_handler(Parent) ->
      tpp_udp_client_handler_init(Parent),
      ?SEV_IPRINT("await start command"),
      {ServerSA, Proto, BufInit, Send, Recv} = tpp_udp_handler_await_start(Parent),
      ?SEV_IPRINT("start command with"
                  "~n   ServerSA: ~p", [ServerSA]),
      Domain   = maps:get(family, ServerSA),
      Sock     = tpp_udp_sock_open(Domain, Proto, BufInit),
      Path     = tpp_udp_sock_bind(Sock, Domain),
      ?SEV_IPRINT("announce ready", []),
      tpp_udp_handler_announce_ready(Parent, init),
      {InitMsg, Num} = tpp_udp_handler_await_continue(Parent, send),
  