Was a employee of a company employed by M1 's writer
SELECT count(*) WHERE {
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company ?x1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company ?x2 .
?x1 a ns:business.employer .
?x2 ns:film.writer.film M1
}