Sampling is per-axis and independent, so the coverage of the product is the
product of its axes' coverages – prod(product_coverage(p)).
product_coverage(x, weight = NULL)A ScaleProduct.
Optional weight name, applied to every axis. NULL uses each
axis's own default weight.
A named numeric, one entry per axis.
p <- scale_product(a = scale_example(), b = scale_example2())
product_coverage(p)
#> a b
#> 1 1
prod(product_coverage(p))
#> [1] 1