[Zope] Functions in a python script

Hi, I found a strange behaviour for a small script that runs correctly in pure Python: == SNIP == foo = 'a great text' def bar(): # error below return foo return bar() ==/SNIP== It makes a "NameError" on "foo" !!! If the first line of bar() is "global foo", this does not change anything. How to use python functions inside Zope python scripts ? Is it reserved for External methods ? Should I provide all "globals" as arguments to the function ?