code: def sum_sp_values(self):
          
          if self.values is None:
              ret = IdValues()
          else:
              ret = IdValues({'0': sum(int(x) for x in self.values.values())})
          return ret
docs: return system level values (spa + spb)
  
          input:
          "values": {
              "spa": 385,
              "spb": 505
          },
  
          return:
          "values": {
              "0": 890
          },