Insert execute no longer return new id

[Rettiwer]

        $a = $pdo->insert()
                            ->into("table")
                            ->columns('x', 'y')
                            ->values($x, $y);

        $insertId = $a->execute();

returns

object(PDOStatement)#106 (1) {
["queryString"]=>
string(66) "INSERT INTO table (x, y) VALUES (?, ?)"
}

instead of new id, how to get it in 2.1 version?

[kwhat]

I have updated the docs, it should be $insertId = $a->execute()->lastInsertId();