langchain/chains/combine_documents/refine.py/RefineDocumentsChain/_construct_refine_inputs
class RefineDocumentsChain:    def _construct_refine_inputs(self, doc: Document, res: str) -> Dict[str, Any]:
        return {
            self.document_variable_name: format_document(doc, self.document_prompt),
            self.initial_response_name: res,
        }