How to use the meteomatics.api.query_png_timeseries function in meteomatics

mch_stations = ['STG']  # MeteoSchweiz Station St. Gallen

    limits = api.query_user_features(username, password)

    print("\ntime series:")
    try:
        df_ts = api.query_time_series(coordinates_ts, startdate_ts, enddate_ts, interval_ts, parameters_ts,
                                      username, password, model, ens_select, interp_select,
                                      cluster_select=cluster_select)
        print (df_ts.head())
    except Exception as e:
        print("Failed, the exception is {}".format(e))

    print("\npng timeseries:")
    try:
        api.query_png_timeseries(prefixpath_png_ts, startdate_png_ts, enddate_png_ts, interval_png_ts, parameter_png_ts,
                                 lat_N, lon_W, lat_S, lon_E, res_lat, res_lon, username, password)
    except Exception as e:
        print("Failed, the exception is {}".format(e))

    if limits['area request option']:
        print("\ngrid:")
        try:
            df_grid = api.query_grid(startdate_grid, parameter_grid, lat_N, lon_W, lat_S, lon_E, res_lat, res_lon,
                                     username, password)
            print (df_grid.head())
        except Exception as e:
            print("Failed, the exception is {}".format(e))

        print("\nunpivoted grid:")
        try:
            df_grid_unpivoted = api.query_grid_unpivoted(valid_dates_unpiv, parameters_grid_unpiv, lat_N, lon_W, lat_S,