How to use the xgcm.models.mitgcm.mds_store._MDSDataStore function in xgcm

if read_grid:
                    datasets.insert(0, open_mdsdataset(
                        dirname, iters=None, delta_t=delta_t,
                        read_grid=True, swap_dims=False,
                        prefix=prefix, ref_date=ref_date, calendar=calendar,
                        geometry=geometry,
                        grid_vars_to_coords=grid_vars_to_coords,
                        endian=endian, chunks=chunks,
                        ignore_unknown_vars=ignore_unknown_vars))
                # apply chunking
                ds = xr.auto_combine(datasets)
                if swap_dims:
                    ds = _swap_dimensions(ds, geometry)
                return ds

    store = _MDSDataStore(dirname, iternum, delta_t, read_grid,
                          prefix, ref_date, calendar,
                          geometry, endian,
                          ignore_unknown_vars=ignore_unknown_vars)
    ds = xr.Dataset.load_store(store)

    if swap_dims:
        ds = _swap_dimensions(ds, geometry)

    if grid_vars_to_coords:
        ds = _set_coords(ds)

    # turn all the auxilliary grid variables into coordinates
    # if grid_vars_to_coords:
    #     for k in _grid_variables:
    #         ds.set_coords(k, inplace=True)
    #     ds.set_coords('iter', inplace=True)