code: func (s *Scanner) Scan(addr, hostname string) (Grade, Output, error) {
  	grade, output, err := s.scan(addr, hostname)
  	if err != nil {
  		log.Debugf("scan: %v", err)
  		return grade, output, err
  	}
  	return grade, output, err
  }
docs: // Scan performs the scan to be performed on the given host and stores its result.