question: Which film producer was a American Canadian writer of M1 and M2
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:film.writer.film M1 .
  ?x0 ns:film.writer.film M2 .
  ?x0 ns:people.person.nationality ns:m.09c7w0 .
  ?x0 ns:people.person.nationality ns:m.0d060g
  }