def formula_2017_01_01(foyer_fiscal, period, parameters):
    """
        Dépenses de protections du patrimoine naturel (case 7KC, 7KD, 7KE)
        2017
        """
    f7kc = foyer_fiscal('f7kc', period)
    f7kd = foyer_fiscal('f7kd', period)
    f7ke = foyer_fiscal('f7ke', period)
    return f7kc + f7kd + f7ke
