Debug an ISBN Validator, Lab - User interactions

I finished this lab. Very useful. Thanks. Meanwhile I had challenges with the environment. I want to ask about them:

Q1) The main() function was needed to change to pass the tests. However, I was asked to comment it out for the tests to run. Why? In the previous labs it was not required. Is this lab going to teach us something? Are we supposed to do the same in out-of-the-class tasks?

Q2) to test my main, I typed something like a ‘space’ and removed it so the environment got ready to re-run main(). Do you have any suggestion for me to come across it more authentic?

Lesson URL (copy - paste from your browser’s address bar)

because it runs and there is a pending input() waiting for user input, meaning the code stay paused and the tests that run after the code in the editor are never reached, it is a limitation of our test environment

that’s the thing to do in this environment, we don’t have a Run button that you can use