WC_Product_Attribute::get_variation PHP Method

    public function get_variation()
    {
        return $this->data['variation'];
    }

 /**
  * Filter callback for finding variation attributes.
  * @param  WC_Product_Attribute $attribute
  * @return bool
  */
 private static function filter_variation_attributes($attribute)
 {
     return true === $attribute->get_variation();
 }