message: utils.set_optimization_options: Return options for consistency and to match docs
  Summary:
  Even though the passed options object is modified in-place,
  we return it as well to match the other functions in this
  file and the example code for this function.
  Reviewers: #tensorflow, georgep
diff: @@ -193,6 +193,9 @@ def set_optimization_options(opts,
  waiting before a cross replica sum op is scheduled.
  max_inter_ipu_copies_buffer_size: The maximum number of bytes that can be
  waiting before a inter IPU copy between IPUs is scheduled.
  +
  + Returns:
  + The IpuOptions configuration protobuf.
  """
  # Internally embedding lookups are implemented using multiSlice operations.
  opts.enable_multi_slice_combiner = combine_embedding_lookups
  @@ -201,6 +204,8 @@ def set_optimization_options(opts,
  opts.max_inter_ipu_copies_buffer_size = max_inter_ipu_copies_buffer_size
  return opts
  + return opts
  +
  def set_compilation_options(opts, compilation_options=None):
  """Set the IPU compilation options for the session.
  