我有兩個列表a，b它們之間有一些共同的元素，我想找到那些共同的元素及其數量，為此我編寫了以下程序。import functoolsimport apache_beam as beamfrom apache_beam.runners.interactive.interactive_runner import InteractiveRunnerfrom apache_beam.runners.direct.direct_runner import DirectRunnerfrom apache_beam.options.pipeline_options import PipelineOptionsoptions = PipelineOptions()p = beam.Pipeline(InteractiveRunner(underlying_runner=DirectRunner()), options=options)def form_pair(element, side_input):  for i,e in enumerate(side_input):    if e == element:      return i,ea = ['a','b', 'c', 'c', 'b']b = ['a','a','b', 'c', 'b', 'b','d', 'e', 'f']x0 = p | "0" >> beam.Create(a) | "1" >> beam.Distinct()x1 = beam.pvalue.AsList(x0)x3 = p | "2" >> beam.Create(b)x4 = x3 | "3" >> beam.Map(functools.partial(form_pair, side_input=x1))x5 = x4 | "4" >> beam.combiners.Count.PerKey()r = p.run().wait_until_finish()print(r.get(x5))這給了我以下錯誤TypeError: 'AsList' object is not iterable [while running '3']