code: func (s *Subscription) AutoUnsubscribe(max int) error {
  	if s == nil {
  		return ErrBadSubscription
  	}
  	s.mu.Lock()
  	conn := s.conn
  	s.mu.Unlock()
  	if conn == nil {
  		return ErrBadSubscription
  	}
  	return conn.unsubscribe(s, max, false)
  }
docs: // AutoUnsubscribe will issue an automatic Unsubscribe that is
  // processed by the server when max messages have been received.
  // This can be useful when sending a request to an unknown number
  // of subscribers.