def prds_worked_weekly_idx_rule(M):
    """
    Index is (window, tour type, week) if more than one shift length
    in tour type.

    :param M: Model
    :return: Constraint index rule
    """
    return [(i, t, w) for (i, t) in M.okTourType
            for w in M.WEEKS
            if len(M.tt_length_x[t]) > 1]