code: private void prepareNextIterator()
  	{
  	    if (currentIterator == null || !currentIterator.hasNext())
  	    {
  	        currentIterator = null;
  	        while (iteratorIterator.hasNext())
  	        {
  	            currentIterator = iteratorIterator.next();
  	            if (currentIterator.hasNext())
  	            {
  	                break;
  	            }
  	            currentIterator = null;
  	        }
  	    }
  	}
docs: Prepare the next iterator to use