You can, therefore, save a bunch of data using the exact same method you used to create your text file, but ensure to insert commas and new-lines in the right place. If you then save the file as ...

One more note: Python is ruthlessly obedient. If you just spent 20 hours running a program and you save the file as temp_data.txt. Then later you run something and save it as temp_data.txt - done.