reversed() in Python - what supports it and what doesn't

The function reversed() is built-in in Python, but it doesn't work with all data types

✓ Lists - it works
reversed([1, 2, 3]) returns an iterator
list(reversed([1, 2, 3])) → [3, 2, 1]

✓ Tuples - it also works
reversed((1, 2, 3)) can be easily iterated

✗ Sets - not supported
reversed({1, 2, 3}) → TypeError
Why? Sets don't have a fixed order, so they can't be "reversed"

If you need to reverse a set:
list(reversed(list({1, 2, 3})))