def test_view_failed_delitem(attr):
    adata = gen_adata((10, 10))
    view = adata[5:7, :][:, :5]
    adata_hash = joblib.hash(adata)
    view_hash = joblib.hash(view)

    with pytest.raises(KeyError):
        getattr(view, attr).__delitem__("not a key")

    assert view.is_view
    assert adata_hash == joblib.hash(adata)
    assert view_hash == joblib.hash(view)
def _create_3d_axis():
    """creates a subplot with 3d projection if one does not already exist"""
    from matplotlib.projections import get_projection_class
    from matplotlib import _pylab_helpers

    create_axis = True
    if _pylab_helpers.Gcf.get_active() is not None:
        if isinstance(plt.gca(), get_projection_class('3d')):
            create_axis = False
    if create_axis:
        plt.figure()
        plt.subplot(111, projection='3d')