Filtering dataframe rows by inclusion in a set/list
I've got a dataframe that has text for one of the columns. I'd like to filter by all values that are in a set.

Ie:

```
beatles = people[people['name'] in ['ringo', 'john', 'paul', 'george']]
```

I can't seem to do this and would like to know the canonical way. kthxbye :)
