code: func (s *StanServer) lookupOrCreateChannel(name string) (*channel, error) {
  	cs := s.channels
  	cs.RLock()
  	c := cs.channels[name]
  	if c != nil {
  		if c.activity != nil && c.activity.deleteInProgress {
  			cs.RUnlock()
  			return nil, ErrChanDelInProgress
  		}
  		cs.RUnlock()
  		return c, nil
  	}
  	cs.RUnlock()
  	return cs.createChannel(s, name)
  }
docs: // Looks up, or create a new channel if it does not exist