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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 attention_lm_small():
 """Cheap model. on lm1b_32k: 45M params 2 steps/sec on [GeForce GTX TITAN X] Returns: an hparams object. """

  hparams = attention_lm_base()
  hparams.num_hidden_layers = 4
  hparams.hidden_size = 512
  hparams.filter_size = 2048
  hparams.layer_prepostprocess_dropout = 0.5
  return hparams