code: public function isSelfOrDescendantOf($other) {
     return (
        $this->getLeft() >= $other->getLeft() &&
        $this->getLeft() < $other->getRight() &&
        $this->inSameScope($other)
      );
    }
docs: Returns true if node is self or a descendant.
  
  @param NestedSet
  @return boolean