There's also @biyeun 's https://github.com/dimagi/core-hq/blob/master/corehq/apps/reports/filters/base.py#L126 which I'm finding relatively easy/nice to use (https://github.com/dimagi/hsph-reports/commit/3c78934b7da6b90ccc6d791912d7d8b147d75c2c#L0R93).  It's not async but ultimately for most contexts looking up the entire hierarchy on report load isn't going to have much of a noticeable impact.  Plus, with async there's a UI responsiveness tradeoff.