langchain/chat_models/base.py/BaseChatModel/predict_messages
class BaseChatModel:    def predict_messages(
        self, messages: List[BaseMessage], *, stop: Optional[Sequence[str]] = None
    ) -> BaseMessage:
        if stop is None:
            _stop = None
        else:
            _stop = list(stop)
        return self(messages, stop=_stop)