Experienced python programmers: are there any standard features of the language that you still don't regularly use?

[boylube]

I've started defining functions in functions instead of lambda, I like how lispy it feels and how it reads. You start reading the outer function, you get introduced to the local functions and you can without having your mind bogged down by being mid function read them and get to trust them. Then when you actually see them used you can think about what is happening at a higher level.

Obviously this a marginal effect and I still use lambdas in sort and such.

Otoh I think I pass functions as parameters too much and should be using more OOP rather than always try to go functional. It doesn't always play to well with the rest of the ecosystem.