gistfile1.txt

>>> var = "foo"
>>> print(var)
foo
>>> def bar():
...     var = "bar"
...     print(var)
...
>>> bar()
bar
>>> print(var)
foo
>>> def baz():
...     global var
...     var = "baz"
...     print(var)
...
>>> baz()
baz
>>> print(var)
baz