Namespaces and the timeit module

[Roy Smith]

I'm playing with the timeit module, and can't figure out how to time a 
function call.  I tried:

def foo ():
    x = 4
    return x

t = timeit.Timer ("foo()")
print t.timeit()

and quickly figured out that the environment the timed code runs under 
is not what I expected:

Traceback (most recent call last):
  File "./d.py", line 10, in ?
    print t.timeit()
  File "/usr/local/lib/python2.3/timeit.py", line 158, in timeit
    return self.inner(it, self.timer)
  File "<timeit-src>", line 6, in inner
NameError: global name 'foo' is not defined

In fact, trying to time "print dir()" gets you:

['_i', '_it', '_t0', '_timer']

It seems kind of surprising that I can't time functions.  Am I just not 
seeing something obvious?