def augment_features(data, feature_augmentation):
    """
    Augment features for a given data matrix.
    :param data: Data matrix.
    :param feature_augmentation: Function applied to augment the features.
    :return: Augmented data matrix.
    """
    if data is not None and feature_augmentation is not None:
        if isinstance(feature_augmentation, list):
            for augmentation_function in feature_augmentation:
                data = augmentation_function(data)
        else:
            data = feature_augmentation(data)
    return data