def spendables_for_address(self, address):
        """
        Return a list of Spendable objects for the
        given bitcoin address.
        """
        URL = "%s/addr/%s/utxo" % (self.base_url, address)
        r = json.loads(urlopen(URL).read().decode("utf8"))
        spendables = []
        for u in r:
            coin_value = btc_to_satoshi(str(u.get("amount")))
            script = h2b(u.get("scriptPubKey"))
            previous_hash = h2b_rev(u.get("txid"))
            previous_index = u.get("vout")
            spendables.append(Tx.Spendable(coin_value, script, previous_hash, previous_index))
        return spendables
Return a list of Spendable objects for the
        given bitcoin address.