问如何改变apache光束中的事件时间？

EN

def get_timestamp(data):
    my_date = (data['timestamp']) # date : 2010-09-18......string
    times = datetime.fromisoformat(my_date) #type: datetime.datetime
    return beam.window.TimestampedValue(data, datetime.timestamp(times))

lines = p | 'receive_data' >> beam.io.ReadFromPubSub(
        subscription=known_args.in_topic).with_input_types(str) 
        | 'decode' >> beam.Map(lambda x: x.decode('utf-8')) 
        | 'jsonload' >> beam.Map(lambda x: json.loads(x))

 (lines |'timestamp' >> beam.Map(get_timestamp)
           | 'print timestamp' >> beam.ParDo(PrintFn2())
           | 'window' >> beam.WindowInto(
            window.FixedWindows(10),
            trigger=trigger.AfterWatermark(),
            accumulation_mode=trigger.AccumulationMode.ACCUMULATING
        )
        | 'CountGlobally' >> beam.CombineGlobally(
                beam.combiners.CountCombineFn()
            ).without_defaults() 
    )