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