sys.stdout动态修改时文件对象write属性只读的问题

Question

在Python2中实现了如下一段代码:

from sys import stdout

def write(s):
    old_write(s)

try:
   old_write,stdout.write = stdout.write, write
finally:
   del stdout.write

结果得到如下1个错误:

AttributeError: 'file' object attribute 'write' is read-only

对上述代码要进行如何的修改才能正常运行。