question: Was a company whose employee wrote M2 M1 's employer
query: SELECT count(*) WHERE {
  ?x0 a ns:business.employer .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person ?x1 .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
  ?x1 ns:film.writer.film M2
  }