public function toXML(){

            $oXMLout = new \XMLWriter();
            $oXMLout->openMemory();
            $oXMLout->setIndent(true);
            $oXMLout->setIndentString('    ');


        $oXMLout->startDocument("1.0", 'utf-8');
        $oXMLout->startElement('tasks');

        /**
         * @var \Dlin\Saasu\Task\Task $task
         */
        foreach($this->tasks as $task){
           $oXMLout->writeRaw("\n".$task->toXML());
        }
        $oXMLout->endElement();
        $oXMLout->endDocument();

        $xml = $oXMLout->outputMemory();

        return $xml;
    }