<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sp_sum_values(self):
 """ return sp level values input: "values": { "spa": { "19": "385", "18": "0", "20": "0", "17": "0", "16": "0" }, "spb": { "19": "101", "18": "101", "20": "101", "17": "101", "16": "101" } }, return: "values": { "spa": 385, "spb": 505 }, """

        if self.values is None:
            ret = IdValues()
        else:
            ret = IdValues({k: sum(int(x) for x in v.values()) for k, v in
                            self.values.items()})
        return ret