question: Which actor was a film director that M2 and M3 were executive produced by
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.actor .
  ?x0 a ns:film.director .
  ?x0 ns:film.producer.films_executive_produced M2 .
  ?x0 ns:film.producer.films_executive_produced M3
  }