Returns a list of feature names for byte type features.

  Args:
    example: An example.

  Returns:
    A list of categorical feature names (e.g. ['education', 'marital_status'] )

def get_categorical_feature_names(example):
  """Returns a list of feature names for byte type features.

  Args:
    example: An example.

  Returns:
    A list of categorical feature names (e.g. ['education', 'marital_status'] )
  """
  features = get_example_features(example)
  return sorted([
      feature_name for feature_name in features
      if features[feature_name].WhichOneof('kind') == 'bytes_list'
  ])