question: What was produced by a person employed by M1 , M2 , M3 , and M4 and employed by M5 and M6
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 ns:film.film.produced_by|ns:film.film.production_companies ?x1 .
  ?x1 a ns:people.person .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M4 .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M5 .
  ?x1 ns:people.person.employment_history/ns:business.employment_tenure.company M6
  }