def METHOD_NAME(self, key: str) -> Tuple[zarr.storage.BaseStore, str]:
    """Parses a given *key* which is expected to have format
    "{dataset_id}/{level}.zarr/{*path}" for multi-level datasets and
    "{dataset_id}/{*path}" for other datasets.
    """
    try:
        dataset_id, item_key = key.split("/", maxsplit=1)
    except ValueError:
        raise KeyError(key)
    try:
        dataset = self.datasets[dataset_id]
    except ApiError as e:
        raise KeyError(key) from e
    if isinstance(dataset, MultiLevelDataset):
        try:
            level_dataset_id, item_key = item_key.split("/", maxsplit=1)
            level_dataset_id, _ = level_dataset_id.split(".", maxsplit=1)
            level = int(level_dataset_id)
        except ValueError:
            raise KeyError(key)
        if not (0 <= level < dataset.num_levels):
            raise KeyError(key)
        level_dataset = dataset.get_dataset(level)
        zarr_store = level_dataset.zarr_store.get()
    else:
        zarr_store = dataset.zarr_store.get()
    return zarr_store, item_key