Importing Parent Module and the Child Module
<p>I am testing have this module called hello.py.</p>

<pre><code>#!/usr/bin/python

import os

class hello():
    def say(self):
        print "Hello"
</code></pre>

<p>And I have this test script.</p>

<pre><code>#!/usr/bin/python

import hello

print os.listdir( '/tmp' )
</code></pre>

<p>The test script complains that 'os' is not defined. To make this work, I need to do 'import os' in the test script.</p>

<p>What I don't understand is that I already imported hello.py which imported os already. Shouldn't the test script know that by importing hello.py, it is has already imported os?</p>
