Support for Nested Joins?

Does php-sql-query-builder have support for **nested joins**?

I.e. Can it describe the following query:

```sql
SELECT *
FROM t1
  LEFT JOIN (t2, t3) ON (t1.a = t2.a AND t2.b = t3.b)
```

So the above is `LEFT JOIN` to the results of an `INNER JOIN` between `t2` and `t3`.  Note that this JOIN statement can also be described using standard SQL as `LEFT JOIN (t2 CROSS JOIN t3)`.