What do you mean? The cost of an old nuclear reactors' MWh is 40-50€, that's really competitive.
And unlike solar and wind, it produces anytime. As a French person, not only do I think we were right to build them in the first place, I'm annoyed we stopped in the 2000s after the Chernobyl scare campaign, it's safer than Germany's coal, which also produces radioactive waste and isn't properly regulated, unlike nuclear.
Here is an example of a sensor:
https://media.steelseriescdn.com/blog/posts/why-the-truemove-pro-is-the-best-mouse-sensor/9149970b57824b24a7a4e4e415eb0189.webp
It's the hole in the middle of the mouse.
I've never needed to clean one but others have suggested using a q-tip with isopropyl alcohol to clean it.
You may also wanna clean the glide pads (The rounded shiny parts at the top and bottom) so the mouse glides like new and doesn't "catch" on the table.