timeit

[Duncan Smith]

This is possibly a stupid question, but I need to get this working quickly,
and I guess I'm just too tired / pressured to see what I'm doing wrong.
Clearly (from the output below) I can't pass the statement to an instance of
timeit.Timer, but I can execute it using exec().  Any idea what I need to do
to get this timed (using timeit).  Cheers.

>>> import SDC_table
>>> import subtract
>>> import timeit
>>> t = SDC_table.RandomTable(1, 12, (2,3,4))
>>> s = """\
p = subtract.p_risk(t.values, 10)
"""
>>> tim = timeit.Timer(stmt=s)
>>> tim.timeit(10)

Traceback (most recent call last):
  File "<pyshell#119>", line 1, in -toplevel-
    tim.timeit(10)
  File "C:\Python23\lib\timeit.py", line 158, in timeit
    return self.inner(it, self.timer)
  File "<timeit-src>", line 6, in inner
NameError: global name 'subtract' is not defined

# yet
>>> exec(s)
>>> p
0.242621453769059