async def aget_index_struct(
        self, struct_id: Optional[str] = None
    ) -> Optional[IndexStruct]:
        """
        Asynchronously get an index struct.

        Args:
            struct_id (Optional[str]): index struct id

        """
        if struct_id is None:
            structs = await self.async_index_structs()
            assert len(structs) == 1
            return structs[0]
        else:
            json = await self._kvstore.aget(struct_id, collection=self._collection)
            if json is None:
                return None
            return json_to_index_struct(json)

        Asynchronously get an index struct.

        Args:
            struct_id (Optional[str]): index struct id

        
llama-index-core/llama_index/core/storage/index_store/keyval_index_store.py