'Sweep private keys. Returns a transaction that spends UTXOs from
privkey to a destination address. The transaction is not
broadcasted.'

@command('nw')
def sweep(self, privkey, destination, tx_fee=None, nocheck=False, imax=100):

    tx_fee = satoshis(tx_fee)
    privkeys = (privkey if (type(privkey) is list) else [privkey])
    self.nocheck = nocheck
    dest = self._resolver(destination)
    tx = self.wallet.sweep(privkeys, self.network, self.config, dest, tx_fee, imax)
    return (tx.as_dict() if tx else None)
