Lightstreamer IG python not working for TTV Chart

[kiann00]

Hi there, experts......

Does anyone know what the specific python code/format to get the chart-data for volume 'TTV' and 'LTV' are?

Code below, keeps getting an error 'TypeError: unsupported format string passed to NoneType.format'
But I don't know what format 'TTV' and 'LTV' should be???

# A simple function acting as a Subscription listener
def on_charts_update(item_update):
    # print("price: %s " % item_update)
    print("{stock_name:<19}: Time {UTM:<8} - "
          "Open {BID_OPEN:>5} - High {BID_HIGH:>5} - Low {BID_LOW:>5} - Close {BID_CLOSE:>5} - Vol {TTV:>5}".format(
              stock_name=item_update["name"], **item_update["values"]
          ))