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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def query_unbound_ong(self, base58_address: str) -> int: """ 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. """

        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)