def __init__(self, size, offset=0):
    if size <= 0:
      raise ValueError('The size parameter must be strictly positive.')
    self.size = Duration.of(size)
    self.offset = self.size % Timestamp.of(offset)
dataset/ETHPy150Open GoogleCloudPlatform/DataflowPythonSDK/google/cloud/dataflow/transforms/window.py/FixedWindows.__init__/swapped operands of `%`