code: func (s *DiffIndexScanner) Scan() bool {
  	if !s.prepareScan() {
  		return false
  	}
  
  	s.next, s.err = s.scan(s.from.Text())
  	if s.err != nil {
  		s.err = errors.Wrap(s.err, "scan")
  	}
  
  	return s.err == nil
  }
docs: // Scan advances the scan line and yields either a new value for Entry(), or an
  // Err(). It returns true or false, whether or not it can continue scanning for
  // more entries.