code: func (a *AuthWithRoles) UpsertNodes(namespace string, servers []services.Server) error {
  	if err := a.action(namespace, services.KindNode, services.VerbCreate); err != nil {
  		return trace.Wrap(err)
  	}
  	if err := a.action(namespace, services.KindNode, services.VerbUpdate); err != nil {
  		return trace.Wrap(err)
  	}
  	return a.authServer.UpsertNodes(namespace, servers)
  }
docs: // UpsertNodes bulk upserts nodes into the backend.