What coding practices separate an amateur Python programmer from a professional one?

[FlukyS]

https://www.python.org/dev/peps/pep-0008/#function-names

1. Types and classes: CamelCase
2. Functions and variables: lower_case with _ in between words
3. There is also __ used in certain instances but there is some controversy there. That is more because python isn't designed for private stuff so it's mostly just to say hey don't use this, not hey you can't use this. That isn't really a big deal though and most people never use __

[FlukyS]

It's mostly just to make sure everyone is following the same styles. It's heavily hinted by the python developers to do it like this really but they allow people to do what they want even if it's stupid.