code: func (s *PresenceService) KeepAliveNode(ctx context.Context, h services.KeepAlive) error {
  	if err := h.CheckAndSetDefaults(); err != nil {
  		return trace.Wrap(err)
  	}
  	err := s.KeepAlive(ctx, backend.Lease{
  		ID:  h.LeaseID,
  		Key: backend.Key(nodesPrefix, h.Namespace, h.ServerName),
  	}, h.Expires)
  	return trace.Wrap(err)
  }
docs: // KeepAliveNode updates node expiry