public static function isAttachedTo($model)
	{
		if ( $model instanceof  yii\base\Component) {
			foreach ($model->getBehaviors() as $behavior) {
				if ($behavior instanceof SimpleWorkflowBehavior) {
					return true;
				}
			}
		} else {
			throw new WorkflowException('Invalid argument type : $model must be a BaseActiveRecord');
		}
		return false;
	}