question: Were M2 and M6 executive produced by M3 , M4 , and M5 and executive produced by a Mexican film producer
query: SELECT count(*) WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:people.person.nationality ns:m.0b90_r .
  M2 ns:film.film.executive_produced_by ?x0 .
  M2 ns:film.film.executive_produced_by M3 .
  M2 ns:film.film.executive_produced_by M4 .
  M2 ns:film.film.executive_produced_by M5 .
  M6 ns:film.film.executive_produced_by ?x0 .
  M6 ns:film.film.executive_produced_by M3 .
  M6 ns:film.film.executive_produced_by M4 .
  M6 ns:film.film.executive_produced_by M5
  }