Pythonic way to determine if a string is a number

[Roy Smith]

In article <01aaa1da$0$20629$c3e8da3 at news.astraweb.com>,
 Steven D'Aprano <steve at pearwood.info> wrote:

> Okay, but that surely falls under chapter 18 of the "Advanced Python
> Programming for the Mars Rover" book rather than chapter 5 of "Newbies
> Guide to Python".

Well, sure, but this thread started out with my taking, ahem, exception to 
the statement, "never use bare excepts at all".  I agree that doing so is 
not typical, and not the kind of habit that new programmers should form 
because it's not the kind of situation new programmers are likely to be 
involved in.  But, "never" was too strong a word.