message: Update python wrapper for ffmpeg.decode_audio with `stream` attribute
diff: @@ -31,7 +31,7 @@ _ffmpeg_so = loader.load_op_library(
  def decode_audio(contents, file_format=None, samples_per_second=None,
  - channel_count=None):
  + channel_count=None, stream=None):
  """Create an op that decodes the contents of an audio file.
  Note that ffmpeg is free to select the "best" audio track from an mp4.
  @@ -51,6 +51,9 @@ def decode_audio(contents, file_format=None, samples_per_second=None,
  `contents` have more than this number, then some channels will
  be merged or dropped. If `contents` has fewer than this, then
  additional channels will be created from the existing ones.
  + stream: A string specifying which stream from the content file
  + should be decoded, e.g., '0' means the 0-th stream.
  + The default value is '' which leaves the decision to ffmpeg.
  Returns:
  A rank-2 tensor that has time along dimension 0 and channels along
  @@ -61,7 +64,7 @@ def decode_audio(contents, file_format=None, samples_per_second=None,
  """
  return gen_decode_audio_op_py.decode_audio_v2(
  contents, file_format=file_format, samples_per_second=samples_per_second,
  - channel_count=channel_count)
  + channel_count=channel_count, stream=stream)
  ops.NotDifferentiable('DecodeAudio')
  