def test_modify_uns_in_copy():
    # https://github.com/theislab/anndata/issues/571
    adata = ad.AnnData(np.ones((5, 5)), uns={"parent": {"key": "value"}})
    adata_copy = adata[:3].copy()
    adata_copy.uns["parent"]["key"] = "new_value"
    assert adata.uns["parent"]["key"] != adata_copy.uns["parent"]["key"]
def voltage_fft(title, order, voltage, ax=0):
    """plot FFT harmonics of voltage"""
    if ax == 0:
        ax = plt.gca()
    ax.set_title('{} / V'.format(title))
    ax.grid(True)
    if max(order) < 5:
        order += [5]
        voltage += [0]
    try:
        bw = 2.5E-2*max(order)
        ax.bar(order, voltage, width=bw, align='center')
    except ValueError:  # empty sequence
        pass