Excluding all but a single subdirectory from a file search
===

I have a directory structure that resembles the following:

    Dir1
    Dir2
    Dir3
    Dir4
        L SubDir4.1
        L SubDir4.2
        L SubDir4.3

I want to generate a list of files (with full paths) that include all the contents of `Dirs1-3`, but only `SubDir4.2` inside `Dir4`. The code I have so far is

    import fnmatch
    import os
    
    for root dirs, files in os.walk( '.' )
        if 'Dir4' in dirs:
            if not 'SubDir4.2' in 'Dir4':
                dirs.remove( 'Dir4' )
        for file in files
            print file

My problem is that the part where I attempt to exclude any file that does not have `SubDir4.2` in it's path is excluding everything in `Dir4`, including the things I would like to remain. How should I amend that above to to do what I desire?
