question: What film that M2 and M3 directed was executive produced by M1
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.film .
  ?x0 ns:film.film.directed_by M2 .
  ?x0 ns:film.film.directed_by M3 .
  ?x0 ns:film.film.executive_produced_by M1
  }