def test_view_retains_ndarray_subclass():
    adata = ad.AnnData(np.zeros((10, 10)))
    adata.obsm["foo"] = np.zeros((10, 5)).view(NDArraySubclass)

    view = adata[:5, :]

    assert isinstance(view.obsm["foo"], NDArraySubclass)
    assert view.obsm["foo"].shape == (5, 5)
def test_impl():
            A = np.array([1., 2., 3.])
            A[0] = np.nan
            df = pd.DataFrame({'A': A})
            B = df.A.fillna(5.0)
            return B.sum()