def METHOD_NAME(edi_file_list, freq, save_path=None):
    """
    Plot Phase Tensor Map in Lat-Long (unprojected) Coordinate system
    :param edi_file_list: a list of edi files
    :param freq: the frequency value (within a certain tolerance ftol)
    :param save_path: path to file/dir to save the plot as jpg or png file
    :return:
    """
    # 1) Define plots params
    # parameters describing ellipses, differ for different map scales: deg, m, km
    # Try different size to find a suitable value for your case. as a
    # guidance: 1 degree=100KM
    ellipse_dict = {
        'size': 0.2,
        'colorby': 'phimin',
        'range': (
            0,
            90,
            1),
        'cmap': 'mt_bl2gr2rd'}
    # adjust to suitable size: parameters describing the induction vector arrows
    arrow_dict = {'size': 0.5,
                  'lw': 0.2,
                  'head_width': 0.04,
                  'head_length': 0.04,
                  'threshold': 0.8,
                  'direction': 0}
    # parameters describing the arrow legend (not necessarily used)
    # arrow_legend_dict = {'position': 'upper right',
    #                      'fontpad': 0.0025,
    #                      'xborderpad': 0.07,
    #                      'yborderpad': 0.015}
    # 2) Construct plotting object
    pt_obj = PlotPhaseTensorMaps(fn_list=edi_file_list,
                                 plot_freq=freq,
                                 ftol=0.10,  # freq tolerance,which will decide how many data points included
                                 mapscale='deg',  # deg or m, or km
                                 xpad=0.4,  # plot margin; change according to lat-lon in edifiles
                                 ypad=0.4,  # ~ 2* ellipse size
                                 ellipse_dict=ellipse_dict,
                                 plot_tipper='yr',
                                 arrow_dict=arrow_dict,
                                 # arrow_legend_dict=arrow_legend_dict,
                                 # fig_spython examples/plot_phase_tensor_map.py tests/data/edifiles/ 10 /e/MTPY2_Outputs/ptmap3deg.pngize=(6, 5),
                                 # fig_dpi=300, the default is OK. Higher dpi
                                 # may distort figure
                                 save_fn=save_path)
    # 3) do the plot and save figure - if the param save_path provided
    path2figure = pt_obj.plot(save_path=save_path)
    pt_obj.export_params_to_file(save_path=save_path)
    print ("Please check your output figure: %s" % path2figure)
    return