Error trying to get box and box type

i am trying to get the box and box type using pymp4 using the following

```
    boxes = Box.parse_stream(io.BytesIO(data))
    for box in boxes:
        if box.type == b"senc":
            print("found")
```

but all i get is string dosent have type error and i dont see a lot of documentation on this project and how it can be used apart from a few examples