def __init__(self, source):
    self.source = source
    self.start_offset = self.source.start_offset or 0
    self.end_offset = self.source.end_offset
    self.current_offset = self.start_offset
dataset/ETHPy150Open GoogleCloudPlatform/DataflowPythonSDK/google/cloud/dataflow/io/fileio.py/TextFileReader.__init__/original