Difference '-' operator giving confusing answer

Question

first = {1, 2, 3, 4, 5, 6}
second = {4, 5, 6, 7, 8, 9}

print(second - first)

#---------------------
#OUTPUT>> {8, 9, 7}
#Why not {7, 8, 9} ?

Answer 1

A set is an "unordered" collection of items.
That explains a lot.

Answer 2

Hallox is right. Python probably intentionally jumbles the set, to remind people ☺

Answer 3

I'm no in

Answer 4

bbm mo

Answer 5

bbm mo

Answer 6

bbm mo