def METHOD_NAME(range_km, unfolded_phidp, refl, phidp, kdp, filename):
    """
    Make and save a plot of PhiDP, reflectivity and KDP.
    Parameters
    ----------
    range_km : array
        Gate range in kilometers.
    unfolded_phidp, refl, phidp, kdp : dict
        Dictionary containing the unfolded phiDP, reflectivity,
        LP filtered phiDP and KDP in the data key
    filename :
        Filename to save the file to.
    """
    from matplotlib import pyplot as plt
    fig = plt.figure(figsize=[10, 5])
    ax = fig.add_subplot(111)
    # filtered phidp and unfolded phidp
    (p1,) = ax.plot(range_km, phidp["data"][0], "b-")
    (p2,) = ax.plot(range_km, unfolded_phidp["data"][0], "g-")
    # set labels
    ax.set_ylim(0, 250)
    ax.set_ylabel("Differential phase shift (degrees)")
    ax.set_xlabel("Range (km)")
    # plot KDP and reflectivity on second axis
    ax2 = ax.twinx()
    (p3,) = ax2.plot(range_km, kdp["data"][0], "r-")
    (p4,) = ax2.plot(range_km, refl["data"][0] / 10.0)
    # decorate and save
    ax2.yaxis.grid(color="gray", linestyle="dashed")
    ax.legend(
        [p1, p2, p3, p4],
        ["Filtered phiDP", "Unfolded phiDP", "KDP", "Z/10.0"],
        loc="upper left",
    )
    fig.savefig(filename)