I have a category list with parent - child relationship:

```
class Categories(models.Model):
  cat_name = models.Charfield()
  cat_parent = models.ForeignKey('self')

```

So i want to list them as such:

```
Category 1
  Sub category 1
  Sub category 2
  Sub category 3
Category 2
  Sub category 4
  Sub category 5

```

etc...

What's the best way to do this?