docs: def custom_scale_mixture_prior_builder(getter, name, *args, **kwargs):
    """A builder for the gaussian scale-mixture prior of Fortunato et al.
  
    Please see https://arxiv.org/abs/1704.02798, section 7.1
  
    Args:
      getter: The `getter` passed to a `custom_getter`. Please see the
        documentation for `tf.get_variable`.
      name: The `name` argument passed to `tf.get_variable`.
      *args: Positional arguments forwarded by `tf.get_variable`.
      **kwargs: Keyword arguments forwarded by `tf.get_variable`.
  
    Returns:
      An instance of `tfp.distributions.Distribution` representing the
      prior distribution over the variable in question.
    """
    # This specific prior formulation doesn't need any of the arguments forwarded
    # from `get_variable`.
    del getter
    del name
    del args
    del kwargs
    return CustomScaleMixture(
        FLAGS.prior_pi, FLAGS.prior_sigma1, FLAGS.prior_sigma2)