scope in nested function calls

I've just moved a piece of code out of a long function into another (lower 
nested) function and I'd like the lower nested function to still access (write 
to) variables in the calling function. I'm doing this for readability and so 
that I can test a couple of different versions of the lower nested function by 
commenting out calls in the calling function.

Here's an example piece of code
-------------------------------
#! /usr/bin/python

def foo():
         print "foo: bar_value  %d" %bar_value

def bar():
         bar_value=1
         print "bar: bar_value  %d" %bar_value
         foo()

#main()
bar()

---------

the output is

# ./test_scope.py
bar: bar_value  1
Traceback (most recent call last):
   File "./test_scope.py", line 12, in ?
     bar()
   File "./test_scope.py", line 9, in bar
     foo()
   File "./test_scope.py", line 4, in foo
     print "foo: bar_value  %d" %bar_value
NameError: global name 'bar_value' is not defined

-------------

I can't use "global bar_value" inside foo(), since bar_value isn't global. 
bar_value isn't local, enclosed, global or built-in (AFAIK).

Is there a way to write to variables in a calling function? (If I have to pass 
all variables as parameters, I'd rather leave the code inside the original 
function).

Thanks Joe

--

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Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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