code: def query_unbound_ong(self, base58_address: str) -> int:
          
          contract_address = self.get_asset_address('ont')
          unbound_ong = self.__sdk.rpc.get_allowance("ong", Address(contract_address).b58encode(), base58_address)
          return int(unbound_ong)
docs: This interface is used to query the amount of account's unbound ong.
  
          :param base58_address: a base58 encode address which indicate which account's unbound ong we want to query.
          :return: the amount of unbound ong in the form of int.