If you're going to program in Python, then you'll need to understand how Python's functions work. After all, you'll be writing functions, and want to do so in the best way possible. And you'll be reading and maintaining other people's functions — so knowing how they work will definitely help. By the end of WPE A2, you'll have a thorough grounding in Python functions, and will be able to use them the way they were meant to be used.