static public function append($root, $data, $options=[])
    {
        $rootString = static::root($root);
        $rootNode = simplexml_load_string($rootString);
        
        return static::addDataToNode($rootNode, $data)->asXML();
    }
static public function append($root, $data, $options=[])
    {
        $rootString = static::root($root);
        $rootNode = simplexml_load_string($rootString);
        
        return static::addDataToNode($rootNode, $data)->asXML();
    }
static public function append ( $ root , $ data , $ options = [ ] ) { $ rootString = static :: root ( $ root ) ; $ rootNode = simplexml_load_string ( $ rootString ) ; return static :: addDataToNode ( $ rootNode , $ data ) -> asXML ( ) ; }
append data to rootString
@param  string|array $root
@param  string|array $data
@param  array        $options
@return string
append data to rootString