“Hey, kid, what do you want to be when you grow up?”

“I want to be a scientist!” The little boy said softly.

“OK.” The salesperson skillfully tapped on the screen and said, “ Just pay in thirty years. “

Thirty years later, the little boy really became a great scientist. He came to the store with a a lot of money to thank the salesperson. “It’s amazing. How do you control my future destiny?”

“It’s very simple,” the salesperson smiled. “Just find the worlds where you don’t become a scientist from parallel time and space, and then delete those worlds.”