anchor.diff:          log_recv ->
               %% found a receive without a send?
               %% not yet implemented
  -            _ = element(5, X),
  +            io:format("Found receive without send?~n"),
  +          _ = element(5, X),
               DrawTrace;
           log_info ->
               %% print info somewhere
  
positive.code: %% sample call sequence to get a tx trace:
  %% tex traces have to be relatively short, so paste all at once to the
  %% erlang shell.
  %% api_tx:write("b", 1). trace_mpath:start(). api_tx:write("a", 1). trace_mpath:stop(). T = trace_mpath:get_trace(). trace_mpath:to_texfile(T, "trace.tex").
  
  -spec to_texfile(trace(), file:name()) -> ok | {error, file:posix() | badarg | terminated}.
  to_texfile(Trace, Filename) ->
      ScaleX = 30, %% 1 cm is ScaleX microseconds in the plot
      TicsFreq = 50, %% draw x-tics every TicsFreq microseconds
  
      {ok, File} = file:open(Filename, [write]),
      io:format(File,
  
negative.code: -spec normalize_pidinfo(anypid()) -> pidinfo().
  normalize_pidinfo(Pid) ->
      case is_pid(Pid) of
          true ->
              PidName = case pid_groups:group_and_name_of(Pid) of
                            failed -> no_pid_name;
                            Name -> Name
                        end,
              {comm:make_global(Pid), PidName};
          false ->
              case comm:is_valid(Pid) of
                  true ->
                      case comm:is_local(Pid) of
                          true ->
                              PidName =
                                  case pid_groups:group_and_name_of(
                                         comm:make_local(Pid)) of
                                      failed -> no_pid_name;
                                      Name -> Name
                                  end,
                              {Pid, PidName};
                          false -> {Pid, non_local_pid_name_unknown}
                      end;
                  false -> %% already a pidinfo()
  