code: func readDirNames(dirPath string) ([]string, error) {
  	d, err := os.Open(dirPath)
  	if err != nil {
  		return nil, err
  	}
  	defer d.Close()
  
  	names, err := d.Readdirnames(-1)
  	if err != nil {
  		return nil, err
  	}
  	return names, nil
  }
docs: // readDirNames returns a list of all dirents in dirPath.  The result list is
  // not sorted or filtered.