Yes, I was actually looking for the union intersection, etc. functionality. I use that extensively in the project I work on. And it's core enough that I want it in the language, not as a third-party add on because of the performance implications and because of things the language can enforce natively. The Python set data type really is great for a certain class of problems. In particular, graph analysis and traversal.
Lot's of libraries for this on Github; everone (myself included; plug: https://github.com/bulters/readyset) and his mother probably writes one at some point.
As I said, I really want to see it in the core language. Your point about "everone ... and his mother probably writes one at some point" seems like a strong point for just putting it into the language or primary implementation if it's such a common pattern.
