twistup error

python stolenTwistUp.py
Traceback (most recent call last):
  File "stolenTwistUp.py", line 12, in <module>
    print twistUp("THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOG")
  File "stolenTwistUp.py", line 9, in twistUp
    new_s += chr(0x0300 + randint(0, 0x6F))
ValueError: chr() arg not in range(256)