How do you know if you're out of memory?

[R. C. Ellis]

I'm an old programmer... from so far back some of my code appeared on 
the back of a stegesaurus.. (and it was buggy, of course).

Anyway, how do I know if a new Tkinter widget I create has enough memory 
to instantiate?  I'd rather catch an exception or something, rather than 
  gift my user with a wonderful interpreter message.

RC