query: SELECT ?item ?group ?district ?start WHERE {
    ?item wdt:P31 wd:Q5;
      p:P39 ?ps.
    ?ps ps:P39 wd:Q20058778;
      pq:P580 ?start.
    OPTIONAL { ?ps pq:P580 ?start. }
    OPTIONAL { ?ps pq:P582 ?end. }
    OPTIONAL { ?ps pq:P4100 ?group. }
    OPTIONAL { ?ps pq:P768 ?district. }
    FILTER((!(BOUND(?end)))