There are lots of signs that you becoming a intermediate programmer such as :
1. Efficiently using programming language feature (or plugin) rather basic feature. (I believe python has tons of it)
2. Algorithm, either you use a flow that easy to understand or efficient or both (which is, genius).
3. Solve time, you will realize that you can solve problems (and bugs) faster than you in the past.
4. Contributing to open source.
That's only a few things which i can think of. You can find it more when you keep practicing. Cheers.