code: def expires(self):
          
          value = self._properties.get("expirationTime")
          if value is not None:
              # value will be in milliseconds.
              return google.cloud._helpers._datetime_from_microseconds(
                  1000.0 * float(value)
              )
docs: Union[datetime.datetime, None]: The datetime when this model
          expires. If not present, the model will persist indefinitely. Expired
          models will be deleted and their storage reclaimed.