code: def expires(self):
          
          expiration_time = self._properties.get("expirationTime")
          if expiration_time is not None:
              # expiration_time will be in milliseconds.
              return google.cloud._helpers._datetime_from_microseconds(
                  1000.0 * float(expiration_time)
              )
docs: Union[datetime.datetime, None]: Datetime at which the table will be
          deleted.
  
          Raises:
              ValueError: For invalid value types.