/**
  * Run if previous version is < 400
  */
 public function pre_400()
 {
     Avada_AvadaRedux_Migration::get_instance();
     self::clear_twiiter_widget_transients();
 }
 /**
  * Make sure there's only 1 instance of this class running.
  */
 public static function get_instance()
 {
     if (null === self::$instance) {
         self::$instance = new Avada_AvadaRedux_Migration();
     }
     return self::$instance;
 }