aborting without killing the python interpreter

[Russ]

I wrote a simple little function for exiting with an error message:

def error ( message ): print_stack(); exit ("\nERROR: " + message +
"\n")

It works fine for executing as a script, but when I run it
interactively in the python interpreter it kills the interpreter.
That's not what I want. Is there a simple way to have a script
terminate but not have it kill the python interpreter when I run it
interactively? I suspect I may need to use exceptions, but I'm hoping
not to need them. Thanks.