question: Who was a Canadian film director that M2 , M3 , and M4 were directed by
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:people.person .
  ?x0 ns:film.director.film M2 .
  ?x0 ns:film.director.film M3 .
  ?x0 ns:film.director.film M4 .
  ?x0 ns:people.person.nationality ns:m.0d060g
  }