def calc_precipitation_excess(throughfall, canopyDrain):
    """ Calculate excess precipitation (the sum of throughfall and canopy drainage)

    Parameters
    ----------
    throughfall : int or float
        Throughfall flux [mm day^-1]
    canopyDrain : int or float
        Canopy drainage flux [mm day^-1]
    Returns
    -------
    precipExcess : int or float
        Excess precipitation [mm day^-1]
    """

    precipExcess = throughfall + canopyDrain

    return precipExcess