async def adelete_messages(self, key: str) -> Optional[List[ChatMessage]]:
        """
        Delete messages for a key asynchronously.

        Args:
            key: Key to delete messages for

        """
        # Get messages before deleting
        messages = await self.aget_messages(key)

        # Delete all messages for this key
        await self._async_collection.delete_many({"session_id": key})

        return messages

        Delete messages for a key asynchronously.

        Args:
            key: Key to delete messages for

        
llama-index-integrations/storage/chat_store/llama-index-storage-chat-store-mongo/llama_index/storage/chat_store/mongo/base.py