message: Update docstring of tf.sets.difference to include Raises
  This fix updated docstring of tf.sets.difference to include
  conditions that raises exceptions.
  This fix fixes 29897.
diff: @@ -266,6 +266,13 @@ def set_difference(a, b, aminusb=True, validate_indices=True):
  A `SparseTensor` whose shape is the same rank as `a` and `b`, and all but
  the last dimension the same. Elements along the last dimension contain the
  differences.
  +
  + Raises:
  + TypeError: If inputs are invalid types, or if `a` and `b` have
  + different types.
  + ValueError: If `a` is sparse and `b` is dense.
  + errors_impl.InvalidArgumentError: If the shapes of `a` and `b` do not
  + match in any dimension other than the last dimension.
  """
  a, b, flipped = _convert_to_tensors_or_sparse_tensors(a, b)
  if flipped:
  