anchor.diff:              Port -> <<Bin/binary, ?SP, Host/binary, ?HCOLON, (sip_binary:integer_to_binary(Port))/binary>>
           end,
       append_params(Bin2, Via#sip_hdr_via.params);
  -
  -
  -%% ....
  -process(fn, 'cseq', _Ignore) -> <<"CSeq">>;
  -process(p, 'cseq', Bin) ->
  -    {SeqBin, Bin2} = sip_binary:parse_token(Bin),
  -    {MethodBin, <<>>} = sip_binary:parse_token(Bin2),
  -    Sequence = sip_binary:binary_to_integer(SeqBin),
  -    Method = sip_binary:binary_to_existing_atom(sip_binary:to_upper(MethodBin)),
  -    cseq(Sequence, Method);
  -
  -process(f, 'cseq', CSeq) when is_record(CSeq, sip_hdr_cseq) ->
  -    SequenceBin = sip_binary:integer_to_binary(CSeq#sip_hdr_cseq.sequence),
  -    MethodBin = sip_binary:any_to_binary(CSeq#sip_hdr_cseq.method),
  -    <<SequenceBin/binary, " ", MethodBin/binary>>;
   
   %% ....
   process(fn, 'max-forwards', _Ignore) -> <<"Max-Forwards">>;
  
positive.code:      ?_assertEqual([{'content-length', <<"5">>}, {'via', <<"SIP/2.0/UDP localhost">>},
                      {'from', <<"sip:alice@localhost">>}, {'to', <<"sip:bob@localhost">>},
                      {'call-id', <<"callid">>}, {'contact', <<"Alice <sip:example.com>">>},
                      {'supported', <<"100rel">>}, {'content-encoding', <<"gzip">>}],
                     parse_headers(<<"l: 5\r\nv: SIP/2.0/UDP localhost\r\nf: sip:alice@localhost\r\n",
                                     "t: sip:bob@localhost\r\ni: callid\r\nm: Alice <sip:example.com>\r\n",
                                     "k: 100rel\r\ne: gzip\r\n">>)),
       % multi-line headers
       ?_assertEqual([{'subject', <<"I know you're there, pick up the phone and talk to me!">>}],
                     parse_headers(<<"Subject: I know you're there,\r\n               pick up the phone   \r\n               and talk to me!\r\n">>)),
  
negative.code:                      "Authorization: Digest username=\"Alice\"\r\nCall-ID: callid\r\n",
                       "Call-Info: <http://www.example.com/alice/photo.jpg>\r\nContact: *\r\n",
                       "Content-Disposition: session\r\nContent-Encoding: gzip\r\n",
                       "Content-Language: en\r\nContent-Length: 5\r\n",
                       "Content-Type: application/sdp\r\n",
  
                       "Content-Length: 5\r\nVia: SIP/2.0/UDP localhost\r\nFrom: sip:alice@localhost\r\n",
                       "To: sip:bob@localhost\r\n"
  