Derive address using ``RIPEMD160(SHA256(x))``

def derivesha256address(self):
        """ Derive address using ``RIPEMD160(SHA256(x))`` """
        pkbin = unhexlify(repr(self._pubkey))
        addressbin = ripemd160(hexlify(hashlib.sha256(pkbin).digest()))
        return Base58(hexlify(addressbin).decode('ascii'))