Unions,Intersections, and Difference...not in sequence

I entered the following code...

S1 = set([3, 5, 6, 10, 11, 100])
S2 = set([1, 3, 5, 6, 11, 15])
print(S1 | S2)
print(S1 & S2)
print(S1 - S2)

However, when it prints out, the resulting numbers are not sequential, which I believe they should be. Anyone have an idea what the problem is?

--
--
You received this message from the "vim_use" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php

---
You received this message because you are subscribed to the Google Groups "vim_use" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vim_use+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.