return False
    @property
    def ignore_retriever(self) -> bool:
        """Whether to ignore retriever callbacks."""
        return False
    @property
    def ignore_chat_model(self) -> bool:
        """Whether to ignore chat model callbacks."""
        return False
[docs]class AsyncCallbackHandler(BaseCallbackHandler):
    """Async callback handler that can be used to handle callbacks from langchain."""
[docs]    async def on_llm_start(
        self,
        serialized: Dict[str, Any],
        prompts: List[str],
        *,
        run_id: UUID,
        parent_run_id: Optional[UUID] = None,
        tags: Optional[List[str]] = None,
        metadata: Optional[Dict[str, Any]] = None,
        **kwargs: Any,
    ) -> None:
        """Run when LLM starts running."""
[docs]    async def on_chat_model_start(
        self,
        serialized: Dict[str, Any],
        messages: List[List[BaseMessage]],
        *,
        run_id: UUID,
        parent_run_id: Optional[UUID] = None,
        tags: Optional[List[str]] = None,
        metadata: Optional[Dict[str, Any]] = None,
        **kwargs: Any,
    ) -> Any:
        """Run when a chat model starts running."""
        raise NotImplementedError(
            f"{self.__class__.__name__} does not implement `on_chat_model_start`"
        )
[docs]    async def on_llm_new_token(
        self,
        token: str,
        *,
        chunk: Optional[Union[GenerationChunk, ChatGenerationChunk]] = None,
        run_id: UUID,
        parent_run_id: Optional[UUID] = None,