public function parseJSKOS(PrettyJsonSerializable $jskos): EasyRdf_Graph
    {
        if (!$this->context) {
            $this->context = json_decode(file_get_contents(__DIR__.'/jskos-context.json'));
        }
        
        if ($jskos instanceof Set) {
            $json = '{"@graph":'.json_encode($jskos->jsonLDSerialize('', true)).'}';
        } else {
            $json = json_encode($jskos->jsonLDSerialize('', true));
        }

        $rdf = JsonLD::toRdf($json, ['expandContext' => $this->context]);
        # TODO: catch (\ML\JsonLD\Exception\JsonLdException $e)

        $graph = new EasyRdf_Graph();
        $this->parse($graph, $rdf);

        return $graph;
    }