How do I exec a user script and note errors?

[Robert Ferrell]

I want to read in (and execute) a user python file.  I know I can do
that with execfile().  However, I want to catch some errors that the
user might have made.  If I read the file line at a time, and exec
each line, I can use try:/except:.  However, that doesn't work if the
user has function defitions, or other multi-line code blocks in the
file.

What is a good python way to accomplish what I want?

thanks,
-robert