Fun fact: not only is the iteration order of sets in python unordered, it's also undeterministic! A set of the same values, iterated in two python program, could iterate in a different order.

I learned this when a unit test that iterated over a set started failing sporadically :P super confusing bug!

I think this is just for sets whos items hash derive from `hash(some_string)` (eg.: sets of strings)

This is because the string hash function is randomized on process startup to help prevent DOS attacks: https://stackoverflow.com/q/30585108/1517969

You're right! I guess you can't rely on sets being iterated over in order (not that you ever should rely on that). Moreover I was trying to show that you can use lists, tuples, and sets as temporary iterable objects, though but no-one (that I have seen) uses sets in that way.

Sets are more useful when you want to dedupe unknown data. Defining a set with constants to use immediately in a for loop is not very helpful compared to a tuple or a list.

Also, you can make anything iterable in python if you implement __iter__.

Set insertion is O(1). This isn't C++.

I didn't claim it wasn't O(1). I just said that for sets to automatically be sorted like the parent comment claimed, it would have to be O(logn) insertion since that's the fastest you can insert into a sorted data structure. Obviously sets are not sorted, and thus are able to maintain O(1) insertion.

My bad. Didn't read the context. You're right - what that comment is suggesting is insane.