Sample from the Gumbel distribution, protect from overflows.

  Args:
    shape: Shape of Gumbel samples.

  Returns:
    Noise drawn from Gumbel distribution.

def gumbel_sample(shape):
  """Sample from the Gumbel distribution, protect from overflows.

  Args:
    shape: Shape of Gumbel samples.

  Returns:
    Noise drawn from Gumbel distribution.
  """
  uniform_samples = tf.random_uniform(shape, minval=0.00001, maxval=0.99998)
  return -tf.log(-tf.log(uniform_samples))