code: public synchronized TicketBucket getTicketBucket(Region region) {
      	TicketBucket tb = buckets.get(region);
      	if (tb == null) {
      		tb = new TicketBucket(rules);
      		buckets.put(region, tb);
      	}
      	
      	return tb;
      }
docs: Gets the {@link TicketBucket} for the given {@link Region}. Creates
  one if it does not exist.
  
  @param region {@link Region} to retrieve
  @return a {@link TicketBucket} for this {@link Region}