os.path.walk() to get full path of all files

[dude]

My goal is create a list of absolute paths for all files in a given
directory (any number of levels deep).

root
----dir1
--------file1
--------file2
--------dir2
------------file3
--------dir3
-------------dir4
------------------file4
----file5

So the above would return:
[root/dir1/file1, root/dir1/file2, root/dir1/dir2/file3, etc...]

I've been trying different ways of using os.path.walk() for that, but
I can't find an elegant way.  Anyone know of something simple to
accomplish that?