question: Was M3 a film producer whose sibling married M0 , M1 , and M2
query: SELECT count(*) WHERE {
  ?x0 ns:people.person.spouse_s/ns:people.marriage.spouse|ns:fictional_universe.fictional_character.married_to/ns:fictional_universe.marriage_of_fictional_characters.spouses M0 .
  ?x0 ns:people.person.spouse_s/ns:people.marriage.spouse|ns:fictional_universe.fictional_character.married_to/ns:fictional_universe.marriage_of_fictional_characters.spouses M1 .
  ?x0 ns:people.person.spouse_s/ns:people.marriage.spouse|ns:fictional_universe.fictional_character.married_to/ns:fictional_universe.marriage_of_fictional_characters.spouses M2 .
  FILTER ( ?x0 != M0 ) .
  FILTER ( ?x0 != M1 ) .
  FILTER ( ?x0 != M2 ) .
  FILTER ( M3 != ?x0 ) .
  M3 a ns:film.producer .
  M3 ns:people.person.sibling_s/ns:people.sibling_relationship.sibling|ns:fictional_universe.fictional_character.siblings/ns:fictional_universe.sibling_relationship_of_fictional_characters.siblings ?x0
  }