message: [tf.data] Correct / clarify docstring for `weights` as a dataset.
  This is a noop.
diff: @@ -200,10 +200,11 @@ def sample_from_datasets(datasets, weights=None, seed=None):
  Args:
  datasets: A list of @{tf.data.Dataset} objects with compatible structure.
  - weights: (Optional.) A list of `len(datasets)` floating-point values or a
  - @{tf.data.Dataset} object, where `weights[i]` represents the probability
  - with which an element should be sampled from `datasets[i]`. Defaults to a
  - uniform distribution across `datasets`.
  + weights: (Optional.) A list of `len(datasets)` floating-point values where
  + `weights[i]` represents the probability with which an element should be
  + sampled from `datasets[i]`, or a @{tf.data.Dataset} object where each
  + element is such a list. Defaults to a uniform distribution across
  + `datasets`.
  seed: (Optional.) A `tf.int64` scalar `tf.Tensor`, representing the
  random seed that will be used to create the distribution. See
  @{tf.set_random_seed} for behavior.
  