Parameters
    ----------
    proxy : DMFControlBoard
    start_channel : int
        Channel number from which to start a channel sweep (should be a
        multiple of 40, e.g., 0, 40, 80).

    Returns
    -------
    pandas.DataFrame
        See description of return of :func:`sweep_channels`.

def plot_channel_sweep(proxy, start_channel):
    '''
    Parameters
    ----------
    proxy : DMFControlBoard
    start_channel : int
        Channel number from which to start a channel sweep (should be a
        multiple of 40, e.g., 0, 40, 80).

    Returns
    -------
    pandas.DataFrame
        See description of return of :func:`sweep_channels`.
    '''
    test_loads = TEST_LOADS.copy()
    test_loads.index += start_channel

    results = sweep_channels(proxy, test_loads)
    normalized_measurements = (results['measured capacitance']
                               / results['expected capacitance'])
    fig, axis = plt.subplots(figsize=(10, 8))
    axis.bar(normalized_measurements.index - 0.3, normalized_measurements,
             width=0.6, edgecolor='none', facecolor='limegreen')
    axis.set_xlim(left=test_loads.index.min() - 0.5,
                  right=test_loads.index.max() + 0.5)
    axis.set_xlabel('channel')
    axis.set_ylabel(r'$\frac{C_{\tt{measured}}}{C_{\tt{expected}}}$',
                    fontsize=28)
    return results