code: func GetValidatedSources(sources []string) ([]string, error) {
  	validated := make([]string, 0, len(sources))
  	for _, source := range sources {
  		switch source {
  		case AllSource:
  			return []string{FileSource, HTTPSource, ApiserverSource}, nil
  		case FileSource, HTTPSource, ApiserverSource:
  			validated = append(validated, source)
  			break
  		case "":
  			break
  		default:
  			return []string{}, fmt.Errorf("unknown pod source %q", source)
  		}
  	}
  	return validated, nil
  }
docs: // Gets all validated sources from the specified sources.