code: func (l *State) ServiceState(id string) *ServiceState {
  	l.RLock()
  	defer l.RUnlock()
  
  	s := l.services[id]
  	if s == nil || s.Deleted {
  		return nil
  	}
  	return s.Clone()
  }
docs: // ServiceState returns a shallow copy of the current service state record. The
  // service record still points to the original service record and must not be
  // modified. The WatchCh for the copy returned will also be closed when the
  // actual service state is changed.