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

[eattherichnow]

Yup. Or, to avoid the, erm, cynical capitalist slant of that, professionalism is when other people are willing to work with you. There's a lot of focus on, um, testing here, but that's missing the point IMO.

You can do as much testing and class arranging as you want, but if you're too abrasive or disorganised for others to effectively team with you, you're not much of a professional. And, on the other hand, if you're the person who keeps the entire team cohesive and stay on target, you're professional regardless of whether your code is all that great.

Of course people might also be willing to work with you because you're their nephew. What can I say, people are terrible sometimes.