code: func (s *DriveService) List(pageToken string, limit int) (files []*client.File, next string, err error) {
  	req := s.apiservice.Files.List()
  	req.Q(fmt.Sprintf("'%s' in parents and mimeType != '%s'", s.parentID, MimeTypeDriveFolder))
  
  	if pageToken != "" {
  		req.PageToken(pageToken)
  	}
  
  	if limit > 0 {
  		req.MaxResults(int64(limit))
  	}
  
  	result, err := req.Do()
  	if err != nil {
  		return
  	}
  	return result.Items, result.NextPageToken, err
  }
docs: // List returns a list of files. When limit is greater than zero a paginated list is returned
  // using the next response as a pageToken in subsequent calls.