Function handle_trimable_events 

pub async fn handle_trimable_events<F, R, E>(
    db: Database,
    tracker: DynEventLogTrimableTracker,
    log_event_added: Receiver<()>,
    call_fn: F,
) -> Result<(), EventHandlerError<E>>
where
    F: Fn(&mut DatabaseTransaction<'_, NonCommittable>, EventLogEntry) -> R,
    R: Future<Output = Result<(), E>>,
    E: Error + 'static,

Like handle_events, for the trimable part of the log: entries are handed to call_fn and the tracker’s position drives when they can be trimmed.