langchain/vectorstores/base.py/VectorStore/aadd_documents
class VectorStore:    async def aadd_documents(
        self, documents: List[Document], **kwargs: Any
    ) -> List[str]:
        """Run more documents through the embeddings and add to the vectorstore.

        Args:
            documents (List[Document]: Documents to add to the vectorstore.

        Returns:
            List[str]: List of IDs of the added texts.
        """
        texts = [doc.page_content for doc in documents]
        metadatas = [doc.metadata for doc in documents]
        return await self.aadd_texts(texts, metadatas, **kwargs)