question: What film producer directed M3 , wrote M1 and M2 , and wrote a film
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:film.director.film M3 .
  ?x0 ns:film.writer.film ?x1 .
  ?x0 ns:film.writer.film M1 .
  ?x0 ns:film.writer.film M2 .
  ?x1 a ns:film.film
  }