code: func (s *serviceCache) allServices() []*v1.Service {
  	s.mu.Lock()
  	defer s.mu.Unlock()
  	services := make([]*v1.Service, 0, len(s.serviceMap))
  	for _, v := range s.serviceMap {
  		services = append(services, v.state)
  	}
  	return services
  }
docs: // ListKeys implements the interface required by DeltaFIFO to list the keys we
  // already know about.