code: func recursorAddr(recursor string) (string, error) {
  	// Add the port if none
  START:
  	_, _, err := net.SplitHostPort(recursor)
  	if ae, ok := err.(*net.AddrError); ok && ae.Err == "missing port in address" {
  		recursor = fmt.Sprintf("%s:%d", recursor, 53)
  		goto START
  	}
  	if err != nil {
  		return "", err
  	}
  
  	// Get the address
  	addr, err := net.ResolveTCPAddr("tcp", recursor)
  	if err != nil {
  		return "", err
  	}
  
  	// Return string
  	return addr.String(), nil
  }
docs: // recursorAddr is used to add a port to the recursor if omitted.