def _add_anomaly_list_to_axes(anomaly, ax, anomaly_color, anomaly_alpha,
    anomaly_label):
    """Add a list of anomalous event to an axes as spans"""
    for i, event in enumerate(anomaly):
        ax.axvspan(xmin=event[0], xmax=event[1], color=anomaly_color, alpha
            =anomaly_alpha, label=anomaly_label if i == 0 else None)
