anchor.diff:  write_really(Data, {https, _Final}) -> {ok, Data};
   write_really(Data, {net, Writer, _Closer}) -> {Writer(Data), <<>>};
   write_really(Data, {exec, Writer, _Closer}) -> {Writer(Data), <<>>};
  -write_really(Data, {serial, Writer}) -> {Writer(Data), <<>>};
  +write_really(Data, {serial, Writer, _Closer}) -> {Writer(Data), <<>>};
   write_really(Data, Fd) -> {file:write(Fd, Data), <<>>}.
  
positive.code: 
  %% last member find
  -spec last_output(any()) -> any().
  last_output(L) when is_list(L) -> last_output(lists:last(L));
  last_output(F) when is_function(F) -> last_output(F());
  last_output(X) -> X.
  
  
negative.code: close_port(_, return) -> ok;
  close_port(_, {net, _Writer, Closer}) -> Closer();
  close_port(_, {exec, _Writer, Closer}) -> Closer();
  close_port(_, {serial, _Writer, Closer}) -> Closer();
  close_port(Data, {http, Final}) -> Final(Data);
  close_port(_, Fd) -> file:close(Fd).
  
  