 is, of course, if it rains, what happens then? So they have poured tons of money into infrastructure. They've built this massive underwater tank that can hold the equivalent of up to 20 Olympic swimming pools. And the thinking is that if the sewage overflows, then the water would go into that tank. The tank would hold that water for the duration of the Olympic events. Then they would treat the water, then release it into the Seine. But that tank for now hasn't yet been used. So it's untested. It's unclear if it'll actually do the job.