posthog-js supports person.set_once but our backend doesn't. Make sure we can pass through `$set_once` on an `$identify` call, and only set the properties within if the properties aren't already set on the user.
ee/clickhouse/process_event.py
snapshot_data=properties["$snapshot_data"],
                timestamp=ts,
            )
            return
        _capture_ee(
            event_uuid=event_uuid,
            person_uuid=person_uuid,
            ip=ip,
            site_url=site_url,
            team_id=team_id,
            event=data["event"],
            distinct_id=distinct_id,
            properties=properties,
            timestamp=ts,
        )
        timer.stop("process_event_ee")
else:
    def process_event_ee(
        distinct_id: str,
        ip: str,
        site_url: str,
        data: dict,
        team_id: int,
        now: datetime.datetime,
        sent_at: Optional[datetime.datetime],
        event_uuid: UUIDT,
    ) -> None:
        
        return
def log_event(