code: def _make_builder_configs():
    
    text_encoder_configs = [
        None,
        tfds.features.text.TextEncoderConfig(
            name="bytes", encoder=tfds.features.text.ByteTextEncoder()),
        tfds.features.text.TextEncoderConfig(
            name="subwords8k",
            encoder_cls=tfds.features.text.SubwordTextEncoder,
            vocab_size=2**13),
        tfds.features.text.TextEncoderConfig(
            name="subwords32k",
            encoder_cls=tfds.features.text.SubwordTextEncoder,
            vocab_size=2**15),
    ]
    version = "0.1.0"
    configs = []
    for text_encoder_config in text_encoder_configs:
      for data in _DATA_OPTIONS:
        config = LibrispeechConfig(
            version=version, text_encoder_config=text_encoder_config, data=data)
        configs.append(config)
    return configs
docs: Make built-in Librispeech BuilderConfigs.
  
    Uses 4 text encodings (plain text, bytes, subwords with 8k vocab, subwords
    with 32k vocab) crossed with the data subsets (clean100, clean360, all).
  
    Returns:
      `list<tfds.audio.LibrispeechConfig>`