ProductManufacturerCollection example

    public function getTaxes(): TaxCollection
    {
        return new TaxCollection(
            $this->fmap(fn (ProductEntity $product) => $product->getTax())
        );
    }

    public function getManufacturers(): ProductManufacturerCollection
    {
        return new ProductManufacturerCollection(
            $this->fmap(fn (ProductEntity $product) => $product->getManufacturer())
        );
    }

    public function getUnits(): UnitCollection
    {
        return new UnitCollection(
            $this->fmap(fn (ProductEntity $product) => $product->getUnit())
        );
    }