code: func (r *Request) Do() bool {
  	if r.do != 0 {
  		return r.do == doTrue
  	}
  
  	if o := r.Req.IsEdns0(); o != nil {
  		if o.Do() {
  			r.do = doTrue
  		} else {
  			r.do = doFalse
  		}
  		return o.Do()
  	}
  	r.do = doFalse
  	return false
  }
docs: // Do returns if the request has the DO (DNSSEC OK) bit set.