[Zope] lower(), how?

[Peter Bengtsson]

I saw this in your http://www.zope.org/Documentation/Articles/ZODB1

choice=raw_input("Press 'L' to list employees, 'A' to add"
                               "an employee, or 'Q' to quit:")
choice=choice.lower()


I can't get that lower() thing to work. I tried for example:

n = raw_input("Guess a number between 1 and 100")
n.lower()

but I just get

AttributeError: 'string' object has no attribute 'lower'