public function addChild(PolicyNode $node): self
    {
        $id = spl_object_hash($node);
        $node->_parent = $this;
        $this->_children[$id] = $node;
        return $this;
    }
public function addChild(PolicyNode $node): self
    {
        $id = spl_object_hash($node);
        $node->_parent = $this;
        $this->_children[$id] = $node;
        return $this;
    }
public function addChild ( PolicyNode $ node ) : self { $ id = spl_object_hash ( $ node ) ; $ node -> _parent = $ this ; $ this -> _children [ $ id ] = $ node ; return $ this ; }
Add child node.

@param PolicyNode $node
@return self
Add child node .