Consider using a named slice which is pretty cool for readability (even works on py2.6). [Learned about this a few days ago](http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html).

```
>>> a = [0, 1, 2, 3, 4, 5]
>>> LASTTHREE = slice(-3, None)
>>> LASTTHREE
slice(-3, None, None)
>>> a[LASTTHREE]
[3, 4, 5]
```