question: Was M4 written by M5 and M6 and produced by a film editor that M1 , M2 , and M3 employed
query: SELECT count(*) WHERE {
  ?x0 a ns:film.editor .
  ?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
  ?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
  ?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
  M4 ns:film.film.produced_by|ns:film.film.production_companies ?x0 .
  M4 ns:film.film.written_by M5 .
  M4 ns:film.film.written_by M6
  }