python: The pythonic way to walk through a file path

walk_path.py

In [1]: import os

In [2]: dir = '/home/liwei/boxy'

In [3]: sum([[os.path.join(base,file) for file in files] for base,_,files in os.walk(dir)],[])
Out[3]: 
['/home/liwei/boxy/test.html',
 '/home/liwei/boxy/base.css',
 '/home/liwei/boxy/jquery-1.6.4.min.js',
 '/home/liwei/boxy/boxy.css',
 '/home/liwei/boxy/boxy.zip',
 '/home/liwei/boxy/jquery.boxy.js',
 '/home/liwei/boxy/clear_boxy.css',
 '/home/liwei/boxy/images/icon_close.gif',
 '/home/liwei/boxy/images/pop_tbg.gif',
 '/home/liwei/boxy/images/btn.gif',
 '/home/liwei/boxy/bak/boxy_orig.css',
 '/home/liwei/boxy/bak/screen.css']