How Python Reads Your Code

"Here's something important that most beginners don't think about: Python reads your code exactly like you read a book — top to bottom, one line at a time, never skipping ahead. This sounds obvious but it has huge implications. The order you write things in actually matters a lot. If you try to use something before you've defined it, Python will be confused — just like if someone handed you page 50 of a book before you read page 1."