anchor.diff:       ?_assertEqual([foo, bar], parse('require', <<"foo, bar">>)),
        ?_assertEqual(<<"foo, bar">>, format('require', [foo, bar])),
   
  -     ?_assertEqual([foo, bar], parse('supported', <<"foo, bar">>)),
  -     ?_assertEqual(<<"foo, bar">>, format('supported', [foo, bar])),
  -
        ?_assertEqual([foo, bar], parse('unsupported', <<"foo, bar">>)),
        ?_assertEqual(<<"foo, bar">>, format('unsupported', [foo, bar])),
   
  
positive.code:                      "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\nSubject: Need more boxes\r\n",
  
                       "Content-Length: 5\r\nVia: SIP/2.0/UDP localhost\r\n",
                       "To: sip:bob@localhost\r\n"
                       "x-custom-atom: 25\r\nAllow: INVITE, ACK, CANCEL, OPTIONS, BYE\r\n",
                       "Supported: 100rel\r\nUnsupported: bar, baz\r\n",
                       "X-Custom: value\r\n">>,
                     format_headers([{'accept', <<"*/*">>}, {'accept-encoding', <<"identity">>},
                                     {'accept-language', <<"en">>}, {'alert-info', <<"<http://www.example.com/sounds/moo.wav>">>},
  
negative.code:      % 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">>)),
  
       % Supported
       ?_assertEqual([foo, bar], parse('supported', <<"foo, bar">>)),
       ?_assertEqual(<<"foo, bar">>, format('supported', [foo, bar])),
  
  
  
  
       % To
       ?_assertEqual(address(<<"Bob Zert">>, <<"sip:bob@biloxi.com">>, [{'tag', <<"1928301774">>}]),
  