def persist(
        self, persist_path: str, fs: Optional[fsspec.AbstractFileSystem] = None
    ) -> None:
        """
        Persists the in-memory vector store to a file.

        Args:
            persist_path (str): The path to persist the index.
            fs (fsspec.AbstractFileSystem, optional): Filesystem to persist to.
                (doesn't apply)

        """
        index_path = persist_path or self._index_file_path
        self._index.persist(index_path)

        Persists the in-memory vector store to a file.

        Args:
            persist_path (str): The path to persist the index.
            fs (fsspec.AbstractFileSystem, optional): Filesystem to persist to.
                (doesn't apply)

        
llama-index-integrations/vector_stores/llama-index-vector-stores-docarray/llama_index/vector_stores/docarray/in_memory.py