Мебиус (подрихтовал в пару к Клейну)

https://blog.alexandreev.com/2017/10/01/%d0%bc%d0%b5%d0%b1%d0%b8%d1%83%d1%81-%d0%bf%d0%be%d0%b4%d1%80%d0%b8%d1%85%d1%82%d0%be%d0%b2%d0%b0%d0%bb-%d0%b2-%d0%bf%d0%b0%d1%80%d1%83-%d0%ba-%d0%ba%d0%bb%d0%b5%d0%b9%d0%bd%d1%83/