code: public boolean isValid(K key, UUID ticket) {
  		if (timeouts.containsKey(key)) {
  			Timeout<K> timeout = timeouts.get(key);
  
  			return timeout.getTicket().equals(ticket);
  		} else {
  			return false;
  		}
  	}
docs: Check whether the timeout for the given key and ticket is still valid (not yet unregistered
  and not yet overwritten).
  
  @param key for which to check the timeout
  @param ticket of the timeout
  @return True if the timeout ticket is still valid; otherwise false