question: Did M4 edit a film directed by a film producer and written by M1 and M2
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 .
  ?x1 a ns:film.producer .
  M4 ns:film.editor.film ?x0
  }