code: public static function getInstance()
      {
          $class = get_called_class();
          return isset(Yii::$app->loadedModules[$class]) ? Yii::$app->loadedModules[$class] : null;
      }
docs: Returns the currently requested instance of this module class.
  If the module class is not currently requested, `null` will be returned.
  This method is provided so that you access the module instance from anywhere within the module.
  @return static|null the currently requested instance of this module class, or `null` if the module class is not requested.