Add sufficient inputs from given <wifs> to cover <rawtx> outputs
        and <fee>. If no <change_address> is given, change will be sent to
        first wif.

def add_inputs(self, rawtx, wifs, change_address=None, fee=10000,
                   dont_sign=False):
        """Add sufficient inputs from given <wifs> to cover <rawtx> outputs
        and <fee>. If no <change_address> is given, change will be sent to
        first wif.
        """
        tx = deserialize.tx(rawtx)
        keys = deserialize.keys(self.testnet, wifs)
        fee = deserialize.positive_integer(fee)
        if change_address is not None:
            change_address = deserialize.address(self.testnet, change_address)
        tx = control.add_inputs(self.service, self.testnet, tx, keys,
                                change_address=change_address, fee=fee)

        if not dont_sign:
            tx = control.sign_tx(self.service, self.testnet, tx, keys)

        return serialize.tx(tx)