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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 imagetransformer_b12l_8h_b256_uncond_dr03_tpu():
 """TPU related 12 layer 8 heads model."""

  hparams = imagetransformer_bas8l_8h_big_uncond_dr03_imgnet()
  update_hparams_for_tpu(hparams)
  hparams.batch_size = 2
  hparams.num_heads = 8   # heads are expensive on tpu
  hparams.num_decoder_layers = 12
  hparams.block_length = 256
  hparams.hidden_size = 512
  hparams.filter_size = 2048
  hparams.layer_preprocess_sequence = "none"
  hparams.layer_postprocess_sequence = "dan"
  hparams.layer_prepostprocess_dropout = 0.3
  return hparams