# LoadingCallable

> **Class** in `langchain_classic`

📖 [View in docs](https://reference.langchain.com/python/langchain-classic/chains/qa_with_sources/loading/LoadingCallable)

Interface for loading the combine documents chain.

## Signature

```python
LoadingCallable()
```

## Extends

- `Protocol`

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[View source on GitHub](https://github.com/langchain-ai/langchain/blob/9f232caa7a8fe1ca042a401942d5d90d54ceb1a6/libs/langchain/langchain_classic/chains/qa_with_sources/loading.py#L33)