question: Did a film producer employ M1 , employ M2 , employ M3 , and employ M4
query: SELECT count(*) WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M2 .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M3 .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M4
  }