Body cutting show, cut yourself body magic illusion

https://youtu.be/MPGP31Nv9oU   In the magic show, there are many horrifying magic tricks, and “human cutting” is one of them. The performer lies on the table, and a sharp knife cuts the performer in two. A lot of people were scared, but in the next period, the magician magically combined again, which surprised many people. How do they do it?