public function coupons()
    {
        $coupons = [];

        foreach ($this->transaction->discounts as $discount) {
            $coupons[] = $discount->id;
        }

        return $coupons;
    }
public function coupons()
    {
        $coupons = [];

        foreach ($this->transaction->discounts as $discount) {
            $coupons[] = $discount->id;
        }

        return $coupons;
    }
public function coupons ( ) { $ coupons = [ ] ; foreach ( $ this -> transaction -> discounts as $ discount ) { $ coupons [ ] = $ discount -> id ; } return $ coupons ; }
Get the coupon codes applied to the invoice.

@return array
Get the coupon codes applied to the invoice .