anchor.diff:              {ok, {{_Version, 200, _ReasonPhrase}, _Headers, Body}} =
                 http:request(post,
                              {"http://" ++ Host ++ Path,
  -                            [{"User-Agent", "Erlang/thrift_http_transport"}],
  +                            [{"User-Agent", "Erlang/thrift_http_transport"} | ExtraHeaders],
                               "application/x-thrift",
                               WBinary},
                              HttpOptions,
  
positive.code:                          path, % string()
                           read_buffer, % iolist()
                           write_buffer, % iolist()
                           http_options % see http(3)
                          }).
  
  %%====================================================================
  
negative.code:                                  path = Path,
                                   read_buffer = Rbuf,
                                   write_buffer = Wbuf,
                                   http_options = HttpOptions,
                                   extra_headers = ExtraHeaders}) ->
      case iolist_to_binary(Wbuf) of
          <<>> ->
              %% Don't bother flushing empty buffers.
  