question: Were M2 , M3 , and M4 executive produced by a Mexican film director
query: SELECT count(*) WHERE {
  ?x0 a ns:film.director .
  ?x0 ns:people.person.nationality ns:m.0b90_r .
  M2 ns:film.film.executive_produced_by ?x0 .
  M3 ns:film.film.executive_produced_by ?x0 .
  M4 ns:film.film.executive_produced_by ?x0
  }