def split(sorted_data_points, attr_index, split_value):
    """Splits a list of data points sorted by a given element into two
    lists with one list containing tuples <= split_value and one list
    containing tuples > split_value.
    :param sorted_data_points: List of data points sorted by their values
    of the attribute specified by attr_index.
    :param attr_index: Index of the attribute of the tuple used to
    specify order of tuples.
    :param split_value: Value of tuple attribute where list of data points
    is split.
    :return: List containing two lists of data points as specified above."""
    for index, value in enumerate(sorted_data_points):
        if value[attr_index] > split_value:
            return [sorted_data_points[:index], sorted_data_points[index:]]
    return [sorted_data_points, []]