public function getAllValuesString(Node $node = null, $property) {
        $allValues = $this->getAllValues($node, $property);
        $output = [];
        foreach ($allValues as $a)
            if (is_a($a, 'ML\JsonLD\Node'))
                $output[] = $a->getId();
            else
                $output[] = $a->getValue();

        return $output;
    }