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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 evolved_transformer_big_tpu():
 """Big parameters for Evolved Transformer model on TPU."""

  hparams = add_evolved_transformer_hparams(transformer.transformer_big_tpu())
  hparams.learning_rate_constant = 1 / hparams.learning_rate_warmup_steps ** 0.5
  hparams.learning_rate_schedule = (
      "constant*single_cycle_cos_decay")
  return hparams