public static IGraph GetContextualGraph(this SparqlRemoteEndpoint endpoint, string subject)
=> endpoint.Construct("CONSTRUCT { <" + subject + "> ?p1 ?o1 . ?s2 ?p2 <" + subject + "> . } WHERE { { <" + subject + "> ?p1 ?o1 . } UNION { ?s2 ?p2 <" + subject + "> . } }");
