question: Was a film edited by M3 , written by M1 , and written by M2
query: SELECT count(*) WHERE {
  ?x0 a ns:film.film .
  ?x0 ns:film.film.edited_by M3 .
  ?x0 ns:film.film.written_by M1 .
  ?x0 ns:film.film.written_by M2
  }