Is it a thread execution for future promise

Question

Hi

Refer code having future and promise. Is this code a multithreaded ?

When thread will execute the function in different thread ?

The line when Getvalue is called from main thread ? If so, isn't this single thread ?

Or

Line where get() on future is called.
https://sololearn.com/compiler-playground/cJYxmjXDhz83/?ref=app