def read_documents(pipeline, uris):
  """Read the documents at the provided uris and returns (uri, line) pairs."""
  pcolls = []
  for uri in uris:
    pcolls.append(
        pipeline
        | df.io.Read('read: %s' / uri, df.io.TextFileSource(uri))
        | df.Map('withkey: %s' % uri, lambda v, uri: (uri, v), uri))
  return pcolls | df.Flatten('flatten read pcolls')
dataset/ETHPy150Open GoogleCloudPlatform/DataflowPythonSDK/google/cloud/dataflow/examples/complete/tfidf.py/read_documents/operator `%` -> `/`