Suppose I have:

```
Class Level1:
    name = CharField()

Class Level2:
    name = CharField()
    level1 = ForeignKey(Level1)

Class Level3:
    name = CharField()
    level2 = ForeignKey(Level2)

Class Level4:
    name = CharField()
    level3 = ForeignKey(Level3)

```

Suppose I already have an Level1 object: level1, how can get all Level4 objects of Level1?

Like the meaning: level1.level2\_set.level3\_set.level4\_set.