message: Document AssertNextDataset op
diff: op {
  graph_op_name: "AssertNextDataset"
  visibility: HIDDEN
  + in_arg {
  + name: "input_dataset"
  + description: <<END
  +A variant tensor representing the input dataset.
  +`AssertNextDataset` passes through the outputs of its input dataset.
  +END
  + }
  + in_arg {
  + name: "transformations"
  + description: <<END
  +A `tf.string` vector `tf.Tensor` identifying the transformations that are
  +expected to happen next.
  +END
  + }
  + summary: "A transformation that asserts which transformations happen next."
  + description: <<END
  +Core C++ implementation of the transformation `assert_next()`, which is
  +an internal component of `tf.data`'s Python API.
  +This transformation checks whether the Pascal-case names (i.e. "FlatMap", not
  +"flat_map") of the transformations immediately after it match the list of names
  +in the `transformations` argument. The transformation raises an exception if
  +it finds any discrepancies.
  +The check occurs immediately before iterating over the results of the
  +root dataset, which means that the check happens *after* any `tf.data`
  +optimizations or static optimizations are applied to the dataflow graph.
  +END
  }
  