on_chat_model_start

on_chat_model_start(
  self,
  serialized: Dict[str, Any],
  messages: List[List[BaseMessage]],
  *,
  run_id: UUID,
  parent_run_id: Union[UUID, None] = None,
  tags: Union[List[str], None] = None,
  metadata: Union[Dict[str, Any], None] = None,
  **kwargs: Any = {}
) -> Any