Did a person edit M1 , direct M3 's prequel , and edit M2
SELECT count(*) WHERE {
?x0 a ns:people.person .
?x0 ns:film.director.film ?x1 .
?x0 ns:film.editor.film M1 .
?x0 ns:film.editor.film M2 .
?x1 ns:film.film.sequel M3
}