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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 stochastic_kl_builder(posterior, prior, sample):
 """A pre-canned builder for a ubiquitous stochastic KL estimator."""

  return tf.subtract(
      tf.reduce_sum(posterior.log_prob(sample)),
      tf.reduce_sum(prior.log_prob(sample)))