message: [tfgan] Remove outdated estimator TODO
  Training discriminator and generator with different ratios can already be done using `get_hooks_fn`.
  This was resolved in
diff: @@ -53,9 +53,6 @@ _summary_type_map = {
  }
  -# TODO(joelshor): For now, this only supports 1:1 generator:discriminator
  -# training sequentially. Find a nice way to expose options to the user without
  -# exposing internals.
  class GANEstimator(estimator.Estimator):
  """An estimator for Generative Adversarial Networks (GANs).
  