When making join(t)
function for both non-daemon thread and daemon thread, the main thread (or main process) should wait t
seconds, then can go further to work on its own process. During the t
seconds waiting time, both of the children threads should do what they can do, such as printing out some text. After the t
seconds, if non-daemon thread still didn't finish its job, and it still can finish it after the main process finishes its job, but for daemon thread, it just missed its opportunity window. However, it will eventually die after the python program exits. Please correct me if there is something wrong.