public function isSelfOrDescendantOf(TreeModel $otherNode)
{
// Sanity checks on current node position
if ($this->lft >= $this->rgt) {
throw new TreeInvalidLftRgtCurrent();
}
if ($otherNode->lft >= $otherNode->rgt) {
throw new TreeInvalidLftRgtOther();
}
return $otherNode->lft <= $this->lft && $otherNode->rgt >= $this->rgt;
}