The instructions for this exercise include slicing out the middle one-third of a list of numbers from 1 to 21. You can explicitly pass the indices (7 and 14), but I thought it would be fun to calculate them:

```
to_21 = [x for x in range(1, 22)]
middle_third = to_21[(len(to_21) / 3):(len(to_21) * 2 / 3):]
```

Indices must be integers, so if you try this on lists not evenly divisible by 2 or 3 or whatever divisors then you might outsmart yourself. You might be able to use float division and the int() command to account for it.