anchor.diff:  		Expires ->
   			ExpiresStr = httpd_util:rfc1123_date(Expires),
   			Req3 = cowboy_req:set_resp_header(
  -				<<"Expires">>, ExpiresStr, Req2),
  +				<<"expires">>, ExpiresStr, Req2),
   			{Req3, State2}
   	end.
   
  
positive.code: 	end.
  
  not_modified(Req, State) ->
  	Req2 = cowboy_req:delete_resp_header(<<"Content-Type">>, Req),
  	{Req3, State2} = set_resp_etag(Req2, State),
  	{Req4, State3} = set_resp_expires(Req3, State2),
  	respond(Req4, State3, 304).
  
negative.code: 		undefined -> ContentType;
  		Charset -> [ContentType, <<"; charset=">>, Charset]
  	end,
  	Req2 = cowboy_req:set_resp_header(<<"content-type">>, ContentType2, Req),
  	encodings_provided(cowboy_req:set_meta(charset, Charset, Req2), State).
  
  set_content_type_build_params([], []) ->
  