Was M3 executive produced by a American editor of M1 and M2
SELECT count(*) WHERE {
?x0 ns:film.editor.film M1 .
?x0 ns:film.editor.film M2 .
?x0 ns:people.person.nationality ns:m.09c7w0 .
M3 ns:film.film.executive_produced_by ?x0
}