I was hoping that nothing used 3.x anymore, but now that I look, I see a bunch, mostly in non-English languages. :(

```python
>>> Document.objects.filter(html__contains='<span class="for"').count()
5140
>>> Document.objects.filter(html__contains='<span class="for"').filter(html__contains='data-for="fx3').count()
1646
>>> Document.objects.filter(html__contains='<span class="for"').filter(html__contains='data-for="fx3').filter(locale='en-US').count()
46
```

I think that we have dropped support for those, and we could go nix them. Or I could make sure this works with `fx35`.