code: private void reattach(HeapElement el) {
  		if (el.shift()) {
  			queue.add(el);
  		} else if (el.inclusion) {
  			/*
  			 * If we have no live inclusions, then the rest are exclusions which
  			 * we can safely discard.
  			 */
  			if (--nInclusionsRemaining == 0) {
  				queue.clear();
  			}
  		}
  	}
docs: If the given element's iterator has more data, then push back onto the
  heap.
  @param el the element to push back into the heap.