question: Did M6 employ a American executive producer of M0 , M1 , M2 , M3 , and M4
query: SELECT count(*) WHERE {
  ?x0 ns:film.producer.films_executive_produced M0 .
  ?x0 ns:film.producer.films_executive_produced M1 .
  ?x0 ns:film.producer.films_executive_produced M2 .
  ?x0 ns:film.producer.films_executive_produced M3 .
  ?x0 ns:film.producer.films_executive_produced M4 .
  ?x0 ns:people.person.nationality ns:m.09c7w0 .
  M6 ns:business.employer.employees/ns:business.employment_tenure.person ?x0
  }