code: def _references_content(ref_files):
    
    example_spec = {
        "url": tf.FixedLenFeature([], tf.string),
        "content": tf.FixedLenFeature([], tf.string),
    }
    data = {}
    for ex in generator_utils.tfrecord_iterator(
        ref_files, gzipped=True, example_spec=example_spec):
      data[ex["url"]] = text_encoder.to_unicode(ex["content"])
    return data
docs: Returns dict<str ref_url, str ref_content>.