Telling the sex of a python?

Question
I bought a ball python about 6-8 months ago and is now 10-12 months old. I assumed it was a female because the pet store employee kept saying "she". I'm not so sure it's a female now. I've heard that the males only have spurs and the females don't, though, I've heard the females may also have spurs as well. I heard only pythons and boas have the spurs, my boa does not have any spurs but my ball python does. I don't want to "pop" the vent because I'm afraid I may hurt her because I've never done that before. So how can I actually tell if it's a male or female without doing anything to it's vent? (even probing).

Answer
Tiffany,
  Without probing, there is no sure fire way to tell. The males generally have a more tapered tail and the females have more of a fat, stubby tail. I'd say that is 75% accurate. I wouldn't worry about it unless you are going to try to breed him / her.