def save(aggregate)
      new_events = aggregate.changes
      if new_events.any?
        event_sink.sink(new_events,
                        expected_version: aggregate.version - new_events.count)
      end
      aggregate.clear_changes
    end
def save(aggregate)
      new_events = aggregate.changes
      if new_events.any?
        event_sink.sink(new_events,
                        expected_version: aggregate.version - new_events.count)
      end
      aggregate.clear_changes
    end
Save any new events/changes in the provided aggregate to the event sink

 @param aggregate An aggregate instance to be saved