code: func (s *ServiceController) updateLoadBalancerHosts(services []*v1.Service, hosts []*v1.Node) (servicesToRetry []*v1.Service) {
  	for _, service := range services {
  		func() {
  			if service == nil {
  				return
  			}
  			if err := s.lockedUpdateLoadBalancerHosts(service, hosts); err != nil {
  				klog.Errorf("External error while updating load balancer: %v.", err)
  				servicesToRetry = append(servicesToRetry, service)
  			}
  		}()
  	}
  	return servicesToRetry
  }
docs: // updateLoadBalancerHosts updates all existing load balancers so that
  // they will match the list of hosts provided.
  // Returns the list of services that couldn't be updated.