Project(Lateral(BGP( ?s <http://example/p> ?o),
                Project(Extend(AggregationJoin(Aggregation(??agg1: ?sample, SAMPLE,
                                               {},
                                               G1=Group((?sample),
                                                  Project(Extend(Extend(BGP( ?s <http://example/label> ?label),
                                                                 ?sample,
                                                                 sample(?s) ),
                                                          ?label_count,
                                                          count(?label) ),
                                                  {?sample, ?label_count})))),
                               ?sample,
                               ??agg1),
                        {?sample})),
        {?o, ?s, ?sample})