Cliff B actually answered this question in the comments but I want to take the opportunity to discuss the bugginess of VScode. The answer is that at some point the the VScode interface stripped .py from the file name but the terminal continued to run the program with "python einstein.py" so it never occurred to me that it might be the filename. Not the first time. I already submitted "bank.py" but the file and it's directory are gone! I don't know when it disappeared. The VScode application has crashed numerous times so I have learned to copy my code to my desktop frequently.
PPS I just refreshed the page and tried again and this time everything worked. Time spent on just submitting one short piece of code: 3 hours Time it took to write and debug the code: 10 minutes.
I use MX Linux with an enhanced firewall and I log in as a user with minimal privileges if I know that I will be using the Internet. I also have several security extensions on Firefox. So any of these things could be causing VScode to crash and do weird things. Because I really want to take this course, I "trusted" all the tracking and Microsoft scripts in NoScript and Ghostery (something I would never do otherwise). But even so there might still be something about my Firefox setup that is affecting VScode.
P.S. I renamed the file by adding the .py extension and then submitted. It appeared to work; there were no errors. However nothing was submitted, it is not among my submissions and all the code had been stripped from the file. Good thing I was doing backups to my desktop.
PPS I just refreshed the page and tried again and this time everything worked. Time spent on just submitting one short piece of code: 3 hours Time it took to write and debug the code: 10 minutes.