code: protected function filter_nlastchild($n) {
  		if ($this->parent === null) {
  			return false;
  		} else {
  			return ($this->parent->childCount(true) - $this->index(false) === (int) $n);
  		}
  	}
docs: Checks if node matches css query filter ":nth-last-child(n)"
  @param string $n 1-based index
  @return bool
  @see match()
  @access private