Optional parameters in django urls

Question

I want to achieve this in Django

1. List all items
2. Get only one item

def get(self, request, pk, format=None):
    if pk is not None:
         product = self.get_object(pk)
         serializer = ProductSerializer(product)
    else:
         products = Product.objects.all()
         serializer = ProductSerializer(products)
    return Response(serializer.data)

If pk is in URL take only one product if not take all list.

How can I achieve that in URL? What I'm doing is this

re_path(r"(?P<pk>\d+)", ProductView.as_view(), name="product"),

But 'pk' argument is required here. I don't want the pk to be required but optional.

Thanks in advance