langchain/chat_models/anthropic.py/ChatAnthropic/_agenerate
class ChatAnthropic:    async def _agenerate(
        self,
        messages: List[BaseMessage],
        stop: Optional[List[str]] = None,
        run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
    ) -> ChatResult:
        prompt = self._convert_messages_to_prompt(messages)
        params: Dict[str, Any] = {"prompt": prompt, **self._default_params}
        if stop:
            params["stop_sequences"] = stop

        if self.streaming:
            completion = ""
            stream_resp = await self.client.acompletion_stream(**params)
            async for data in stream_resp:
                delta = data["completion"][len(completion) :]
                completion = data["completion"]
                if run_manager:
                    await run_manager.on_llm_new_token(
                        delta,
                    )
        else:
            response = await self.client.acompletion(**params)
            completion = response["completion"]
        message = AIMessage(content=completion)
        return ChatResult(generations=[ChatGeneration(message=message)])