see below:

```python
14:05:03 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> def lookup(foo):
    for num in xrange(1000000):
   ...:         if num in foo:
   ...:             pass
   ...:

14:05:25 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> foo = range(10)

14:05:34 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> %timeit lookup(foo)
1 loops, best of 3: 235 ms per loop

14:05:42 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> foo = set(range(10))

14:05:48 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> %timeit lookup(foo)
10 loops, best of 3: 64 ms per loop

14:05:52 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> foo = range(6)

14:06:04 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> %timeit lookup(foo)
10 loops, best of 3: 168 ms per loop

14:06:16 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> foo = set(range(6))

14:06:26 (mcdonadt@Daniels-MacBook-Pro-2):/Users/mcdonadt
> %timeit lookup(foo)
10 loops, best of 3: 62.3 ms per loop
```