Returns labels for validation.

    Args:
      val_path: path to TAR file containing validation images. It is used to
      retrieve the name of pictures and associate them to labels.

    Returns:
      dict, mapping from image name (str) to label (str).

def _get_validation_labels(val_path):
    """Returns labels for validation.

    Args:
      val_path: path to TAR file containing validation images. It is used to
      retrieve the name of pictures and associate them to labels.

    Returns:
      dict, mapping from image name (str) to label (str).
    """
    labels_path = tfds.core.get_tfds_path(_VALIDATION_LABELS_FNAME)
    with tf.io.gfile.GFile(labels_path) as labels_f:
      labels = labels_f.read().strip().split('\n')
    with tf.io.gfile.GFile(val_path, 'rb') as tar_f_obj:
      tar = tarfile.open(mode='r:', fileobj=tar_f_obj)
      images = sorted(tar.getnames())
    return dict(zip(images, labels))