How to use the nwbwidgets.analysis.spikes.compute_smoothed_firing_rate function in nwbwidgets

def show_psth_smoothed(data, ax, before, after, group_inds=None, sigma_in_secs=.05, ntt=1000,
                       align_line_color=(.7, .7, .7)):

    all_data = np.hstack(data)
    if not len(all_data):
        return
    tt = np.linspace(min(all_data), max(all_data), ntt)
    smoothed = np.array([compute_smoothed_firing_rate(x, tt, sigma_in_secs) for x in data])

    if group_inds is None:
        group_inds = np.zeros((len(smoothed)))
    group_stats = []
    for group in range(len(np.unique(group_inds))):
        this_mean = np.mean(smoothed[group_inds == group], axis=0)
        err = scipy.stats.sem(smoothed[group_inds == group], axis=0)
        group_stats.append({'mean': this_mean,
                            'lower': this_mean - 2 * err,
                            'upper': this_mean + 2 * err})
    for stats, color in zip(group_stats, color_wheel):
        ax.plot(tt, stats['mean'], color=color)
        ax.fill_between(tt, stats['lower'], stats['upper'], alpha=.2, color=color)
    ax.set_xlim([-before, after])
    ax.set_ylabel('firing rate (Hz)')
    ax.set_xlabel('time (s)')