* Check how deep the event is compared to `event_id`, does it *exceed* (greater than) `max_depth`? If yes, skip.
* Check what number child this event is (ordered by `recent_first`) compared to its parent, does it *exceed* (greater than) `max_breadth`? If yes, skip.
* Process the event. If the event has been added to the response array already, do not include it a second time. If an event fails history visibiilty
* Process the event. If the event has been added to the response array already, do not include it a second time. If an event fails history visibility
checks, do not add it to the response array and do not follow any references it may have.