rem: if (_hdr) {
add: if ((_hdr) && (_hdr_len)) {
context: int send_resp(struct sip_msg* _m, int _code, char* _reason, char* _hdr, int _hdr_len){	struct lump_rpl* ptr;		     /* Add new headers if there are any */	if (_hdr) {		ptr = build_lump_rpl(_hdr, _hdr_len);		add_lump_rpl(_m, ptr);	}		sl_reply(_m, (char*)_code, _reason);	return 0;}