code: private void increaseLevel(boolean list)
  	{
  		level++;
  		if(hasData.length == level)
  		{
  			// Grow lists when needed
  			hasData = Arrays.copyOf(hasData, hasData.length * 2);
  			lists = Arrays.copyOf(lists, hasData.length * 2);
  		}
  
  		hasData[level] = false;
  		lists[level] = list;
  	}
docs: Increase the level by one.
  
  @param list