[Tutor] Stopping program execution

[Sean Abrahams]

I have a web script that checks to see if the user has a session
cookie. If not, I want to display a page saying 'no session found,
please login. yadda yadda yadda', and not execute the rest of the
script. Thing is, I check for the session cookie through a separate
module.

import session
id = session.checkSession()
# for example

If there is a session, the id is returned, otherwise the error message
is printed.

Right now, I have the error message printing fine, but it continues to
execute the rest of the script, which is not the behavior I'm looking
for.

How do I halt the script when it detects no session? Or, is there a
better way to do this?

def sessionCheck(session):
    try:
        id = session["id"]

        return id
    except KeyError, e:
        print "content-type: text/html"
        print
        print "No session found."

        # Stop script

Thanks,
--Sean