def set_updated_at
      if Dynamoid::Config.timestamps && !updated_at_changed?
        self.updated_at = DateTime.now.in_time_zone(Time.zone)
      end
    end
def set_updated_at
      if Dynamoid::Config.timestamps && !updated_at_changed?
        self.updated_at = DateTime.now.in_time_zone(Time.zone)
      end
    end
Automatically called during the save callback to set the updated_at time.

 @since 0.2.0