question: Was a film written by M1 , directed by a film editor , and written by M2 and M3
query: SELECT count(*) WHERE {
  ?x0 a ns:film.film .
  ?x0 ns:film.film.directed_by ?x1 .
  ?x0 ns:film.film.written_by M1 .
  ?x0 ns:film.film.written_by M2 .
  ?x0 ns:film.film.written_by M3 .
  ?x1 a ns:film.editor
  }