chr(i) 返回整数i对应的ASCII字符

>>> a
122
>>> b
344
>>> c = chr(a)
>>> c
'z'

假如整数“i”超过了256将会爆出一个错误：

>>> d = chr(b)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: chr() arg not in range(256)
>>>