anchor.diff:                           path, % string()
                            read_buffer, % iolist()
                            write_buffer, % iolist()
  -                         http_options % see http(3)
  +                         http_options, % see http(3)
  +                         extra_headers % [{str(), str()}, ...]
                           }).
   
   %%====================================================================
  
positive.code:                                  path = Path,
                                   read_buffer = Rbuf,
                                   write_buffer = Wbuf,
                                   http_options = HttpOptions}) ->
      case iolist_to_binary(Wbuf) of
          <<>> ->
              %% Don't bother flushing empty buffers.
  
negative.code:                              path = Path,
                               read_buffer = [],
                               write_buffer = [],
                               http_options = [],
                               extra_headers = []},
      ApplyOption =
          fun
              ({http_options, HttpOpts}, State = #http_transport{}) ->
                  State#http_transport{http_options = HttpOpts};
              ({extra_headers, ExtraHeaders}, State = #http_transport{}) ->
                  State#http_transport{extra_headers = ExtraHeaders};
              (Other, #http_transport{}) ->
                  {invalid_option, Other};
              (_, Error) ->
  