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# Documents

These are the core chains for working with documents. They are useful for summarizing documents, answering questions over documents, extracting information from documents, and more.

These chains all implement a common interface:

```python
class BaseCombineDocumentsChain(Chain, ABC):
    """Base interface for chains combining documents."""

    @abstractmethod
    def combine_docs(self, docs: List[Document], **kwargs: Any) -> Tuple[str, dict]:
        """Combine documents into a single string."""

```
import DocCardList from "@theme/DocCardList";

<DocCardList />
