Checking for an "undefined" variable - newbie question

[Dan Rawson]

How do I check if a variable has been defined??

The following don't appear to work:

if variable:

if variable is None:


I have only one (ugly) solution:

try:
     variable
except NameError:
     ...

which works, but is a bit clumsy if I just want to know if the thing already exists.

If there's a more elegant way to check this, that would be great!

Thanks . . . .

Dan