Python function isn't returning variable
<p>I'm doing a python exercise and writing my first function in which I have to return a value... But the value isn't being returned. I'm running the .py file through Terminal on OS X with Python 3.2.3. The final line should be different to the fourth final line, but they are coming out the same. Yet if I print textMessage in the function itself it prints fine.
What am I missing?</p>

<pre><code>def caesarEncipher(textMessage, shift):
    listOfChars = list(textMessage)
    length = len(listOfChars)
    count = 0
    while length != count:
        listOfChars[count] = chr(ord(listOfChars[count])+shift)
        count = count + 1
    textMessage = ''.join(listOfChars)
    return (textMessage)

print ("Please enter your message to cipher:")
textMessage = raw_input()
print ("Please enter the value you wish to shift your message by:") 
shift = int(input())
print "Your original message was:"
print textMessage
caesarEncipher(textMessage, shift)
print "Your message adjusted by a shift of", shift, "is:"
print textMessage
</code></pre>
