def make_mapper(features):
    """Make a DataFrameMapper from a feature or list of features

    Args:
        features (Union[Feature, List[Feature]]): feature or list of features

    Returns:
        DataFrameMapper: mapper made from features
    """
    if not features:
        features = Feature(input=[], transformer=NullTransformer())
    if not iterable(features):
        features = (features, )
    return DataFrameMapper(
        [t.as_input_transformer_tuple() for t in features],
        input_df=True)