If, like me, you are wondering what the calculation was, here is a dummies' guide: https://arxiv.org/pdf/2007.07872.pdf https://arxiv.org/pdf/2007.07872.pdf It

If, like me, you are wondering what the calculation was, here is a dummies' guide: https://arxiv.org/pdf/2007.07872.pdf https://arxiv.org/pdf/2007.07872.pdf It still makes no sense to me, but might help others.