# on_open
`toloka.streaming.observer.PoolStatusObserver.on_open` | [Source code](https://github.com/Toloka/toloka-kit/blob/v0.1.26/src/streaming/observer.py#L224)

```python
on_open(self, callback: Union[Callable[[Pool], None], Callable[[Pool], Awaitable[None]]])
```

