def add_index_struct(self, index_struct: IndexStruct) -> None:
        """
        Add an index struct.

        Args:
            index_struct (IndexStruct): index struct

        """
        key = index_struct.index_id
        data = index_struct_to_json(index_struct)
        self._kvstore.put(key, data, collection=self._collection)

        Add an index struct.

        Args:
            index_struct (IndexStruct): index struct

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