code: func OSFamily(client *govmomi.Client, ref types.ManagedObjectReference, guest string) (string, error) {
  	b, err := EnvironmentBrowserFromReference(client, ref)
  	if err != nil {
  		return "", err
  	}
  	ctx, cancel := context.WithTimeout(context.Background(), provider.DefaultAPITimeout)
  	defer cancel()
  	return b.OSFamily(ctx, guest)
  }
docs: // OSFamily uses the compute resource's environment browser to get the OS family
  // for a specific guest ID.