help!! getting output from another process line by line, using popen

[cout]

Help!!

There are 2 python scripts, one is to print out the output(output.py),
the other is supposed to get std output from output.py line by line.
However, it only get all the result after 40 seconds. Not during the
executing process. Any ideas?

===========output.py==============
#! /usr/bin/python

import time

for i in range(1,20,1):
         print i
         time.sleep(2)

================monitor.py===============
#! /usr/bin/python

import os
import sys, string
cmd="python output.py"

handle = os.popen(cmd, 'r', 1)
for line in handle:
     print line,
handle.close()