如何使用beam on cloud dataflow在数据管道中迭代日期(天/小时/月)？

import apache_beam as beam
from apache_beam.options.pipeline_options import PipelineOptions
from apache_beam.transforms.window import FixedWindows
from datetime import datetime, timedelta

options = PipelineOptions()

class ProcessDateFn(beam.DoFn):
    def process(self, element):
        # 获取当前日期
        current_date = datetime.now().date()
        
        # 迭代日期，可以根据需要进行天/小时/月的迭代
        for i in range(10):  # 迭代10次
            # 计算迭代后的日期
            new_date = current_date - timedelta(days=i)
            
            # 输出迭代后的日期
            yield new_date

with beam.Pipeline(options=options) as p:
    # 从输入源读取数据
    input_data = p | beam.Create([1, 2, 3, 4, 5])
    
    # 应用自定义的DoFn函数处理数据
    output_data = input_data | beam.ParDo(ProcessDateFn())
    
    # 输出结果
    output_data | beam.io.WriteToText('output.txt')