question: Which film producer did M1 found , M2 found , M3 found , and M4 found
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.producer .
  ?x0 ns:organization.organization.founders M1 .
  ?x0 ns:organization.organization.founders M2 .
  ?x0 ns:organization.organization.founders M3 .
  ?x0 ns:organization.organization.founders M4
  }