I thought after using Python for 6 years now there will be no unknown territories for me. I thought I mastered the language. Phew. Far from it.

So, for starters, I learned about *args and **kwargs. I had no idea those exist and not once, not twice but many times over I was passing arguments to a function via a list or dictionary. I can still pass them as a list or dictionary but with that syntax it would be more organized and clean.