How can you print all elements of a box? Is it possible to get the length of it?

**Question**
Please explain the problem you are running into.

I'm trying to figure how to get the length or number of elements in a box.

**Code sample**
```dart
Provide a few simple lines of code to show your problem.
```

**Version**
- Platform: iOS, Android, Mac, Windows, Linux, Web
- Flutter version: [e.g. 1.5.4]
- Hive version: [e.g. 0.5.0]