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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _piecewise_learning_rate(step, boundaries, values):
 """Scale learning rate according to the given schedule. Multipliers are not cumulative. Args: step: global step boundaries: List of steps to transition on. values: Multiplier to apply at each boundary transition. Returns: Scaled value for the learning rate. """

  values = [1.0] + values
  boundaries = [float(x) for x in boundaries]
  return tf.train.piecewise_constant(
      step, boundaries, values, name="piecewise_lr")