code: func (s *DriveService) Get(ctx context.Context, title string) (*client.File, error) {
  	// TODO: use field selectors
  	query := fmt.Sprintf("'%s' in parents and title = '%s'", s.parentID, title)
  	req := s.apiservice.Files.List().Context(ctx).Q(query)
  	files, err := req.Do()
  	if err != nil {
  		return nil, err
  	}
  	if len(files.Items) < 1 {
  		return nil, os.ErrNotExist
  	}
  	return files.Items[0], nil
  }
docs: // Get retrieves a file with its title equal to the provided title and a child of
  // the parentID as given to New. If not found, os.ErrNotExist is returned.