a dummy python question

[Learning Python]

A example in learning Python by Mark Lutz and David Ascher

about function scope

example like this:

>>def outer(x):
     def inner(i):
        print i,
        if i: inner(i-1)
     inner(x)
>>outer(3)

Here supposely, it should report error, because the function inner
cannot see itself since inner is only in local namespace of outer.

but I typed in this in python interface. It works!
it print out:
3 2 1 0


If you turn this into a module file and run this
it print out
3 2 1 0 none

Can anyone explain to me what's going on?

Thanks

BTW: I am using Python 2.3