public function toXml()
    {
        // init
        $result = '';
        $tagName = ($this->namespace == '' ? '' : $this->namespace.':').$this->name;
        $attributes = '';
        foreach ($this->attributes as $attribute) {
            $attributes .= ' '.$attribute->Name.'="'.$attribute->Value.'"';
        }

        // action
        $result .= '<'.$tagName.$attributes.'>';
        foreach ($this->nodes as $node) {
            /** @var INode $node */
            $result .= $node->toXml();
        }
        $result .= '</'.$tagName.'>';

        // return
        return $result;
    }