Removing the bit about commas and exceptions.

I don't imagine anyone is using Python <2.6, and having a section that says if you're using Python 2.6+ use the `as` but if you're using Python <2.7 use the `,` is confusing.

* What happens if you're using Python 2.6 or Python 2.7? Which do you use? (`as`, but it isn't clear).

I decided to remove it entirely to avoid confusion.