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

lon_E, res_lat, res_lon, username, password)
            print (df_grid_unpivoted.head())
        except Exception as e:
            print("Failed, the exception is {}".format(e))

        print("\ngrid timeseries:")
        try:
            df_grid_timeseries = api.query_grid_timeseries(startdate_ts, enddate_ts, interval_ts, parameters_ts, lat_N,
                                                           lon_W, lat_S, lon_E, res_lat, res_lon, username, password)
            print (df_grid_timeseries.head())
        except Exception as e:
            print("Failed, the exception is {}".format(e))

        print("\ngrid as a png:")
        try:
            api.query_grid_png(filename_png, startdate_png, parameter_png, lat_N, lon_W, lat_S, lon_E, res_lat, res_lon,
                               username, password)
            print("filename = {}".format(filename_png))
        except Exception as e:
            print("Failed, the exception is {}".format(e))

    else:
        print("""
Your account '{}' does not include area requests.
With the corresponding upgrade you could query whole grids of data at once or even time series of grids.
Please check http://shop.meteomatics.com or contact us at shop@meteomatics.com for an individual offer.
""".format(username)
              )

    if limits['historic request option'] and limits['area request option']:
        print("\nlighning strokes as csv:")
        try: