public function modifyResource(
        $uri,
        $sparql = "",
        $headers = []
    ) {
        $options = ['http_errors' => false];

        // Set content.
        $options['body'] = $sparql;

        // Set headers.
        $options['headers'] = $headers;
        $options['headers']['content-type'] = 'application/sparql-update';

        return $this->client->request(
            'PATCH',
            $uri,
            $options
        );
    }