What was written by and executive produced by M0 and M1
SELECT DISTINCT ?x0 WHERE {
?x0 ns:film.film.executive_produced_by M0 .
?x0 ns:film.film.executive_produced_by M1 .
?x0 ns:film.film.written_by M0 .
?x0 ns:film.film.written_by M1
}