anchor.diff:                      {'from', <<"sip:alice@localhost">>}, {'to', <<"sip:bob@localhost">>},
                       {'call-id', <<"callid">>}, {'contact', <<"Alice <sip:example.com>">>},
                       {'supported', <<"100rel">>}, {'content-encoding', <<"gzip">>},
  -                    {'content-type', <<"application/sdp">>}],
  +                    {'content-type', <<"application/sdp">>}, {'subject', <<"Need more boxes">>}],
                      parse_headers(<<"l: 5\r\nv: SIP/2.0/UDP localhost\r\n",
                                      "f: sip:alice@localhost\r\nt: sip:bob@localhost\r\n",
                                      "i: callid\r\nm: Alice <sip:example.com>\r\n",
                                      "k: 100rel\r\ne: gzip\r\n",
  -                                   "c: application/sdp\r\n">>)),
  +                                   "c: application/sdp\r\ns: Need more boxes\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">>)),
  
positive.code:                      "Proxy-Require: foo\r\nRecord-Route: <sip:server10.biloxi.com;lr>\r\n",
                       "Reply-To: Bob <sip:bob@biloxi.com>\r\nRequire: foo\r\n",
                       "Retry-After: 120\r\nRoute: <sip:server10.biloxi.com;lr>\r\n",
                       "Server: HomeServer v2\r\n",
  
                       "Content-Length: 5\r\nVia: SIP/2.0/UDP localhost\r\n",
                       "To: sip:bob@localhost\r\n"
  
negative.code:      ?_assertEqual(<<"<sip:p1.example.com;lr>">>,
                     format('route', address(<<>>, <<"sip:p1.example.com;lr">>, []))),
  
       % Server
       ?_assertEqual(<<"HomeServer v2">>, parse('server', <<"HomeServer v2">>)),
       ?_assertEqual(<<"HomeServer v2">>, format('server', <<"HomeServer v2">>)),
       
       % Subject
       ?_assertEqual(<<"Need more boxes">>, parse('subject', <<"Need more boxes">>)),
       ?_assertEqual(<<"Need more boxes">>, format('subject', <<"Need more boxes">>)),
       
  
       % To
       ?_assertEqual(address(<<"Bob Zert">>, <<"sip:bob@biloxi.com">>, [{'tag', <<"1928301774">>}]),
  