langchain/chat_models/openai.py/ChatOpenAI/_create_chat_result
class ChatOpenAI:    def _create_chat_result(self, response: Mapping[str, Any]) -> ChatResult:
        generations = []
        for res in response["choices"]:
            message = _convert_dict_to_message(res["message"])
            gen = ChatGeneration(message=message)
            generations.append(gen)
        llm_output = {"token_usage": response["usage"], "model_name": self.model_name}
        return ChatResult(generations=generations, llm_output=llm_output)