def select_inputs(self, address: str, amount: int) -> dict:
        '''select UTXOs'''

        utxos = []
        utxo_sum = Decimal(-0.01)  # starts from negative due to minimal fee
        for tx in sorted(self.listunspent(address=address), key=itemgetter('confirmations')):

                utxos.append(
                    TxIn(txid=tx['tx_hash'],
                         txout=tx['tx_ouput_n'],
                         sequence=Sequence.max(),
                         script_sig=ScriptSig.unhexlify(tx['script']))
                         )

                utxo_sum += Decimal(int(tx['value']) / 100000000)
                if utxo_sum >= amount:
                    return {'utxos': utxos, 'total': utxo_sum}

        if utxo_sum < amount:
            raise InsufficientFunds('Insufficient funds.')

        raise Exception("undefined behavior :.(")