langchain/chains/loading.py/_load_map_rerank_documents_chain
def _load_map_rerank_documents_chain(
    config: dict, **kwargs: Any
) -> MapRerankDocumentsChain:
    if "llm_chain" in config:
        llm_chain_config = config.pop("llm_chain")
        llm_chain = load_chain_from_config(llm_chain_config)
    elif "llm_chain_path" in config:
        llm_chain = load_chain(config.pop("llm_chain_path"))
    else:
        raise ValueError("One of `llm_chain` or `llm_chain_config` must be present.")
    return MapRerankDocumentsChain(llm_chain=llm_chain, **config)