human
Complete the below
def OSXFontDirectory():

    ''''Return the system font directories for OS X.  This is done by
    starting at the list of hardcoded paths in
    :attr:`OSXFontDirectories` and returning all nested directories
    within them.'
    '''
assistant
#Here is the Python program you requested.
    fontpaths = []
    def add(arg, directory, files):
        fontpaths.append(directory)
    for fontdir in OSXFontDirectories:
        try:
            if os.path.isdir(fontdir):
                os.path.walk(fontdir, add, None)
        except (IOError, OSError, TypeError, ValueError):
            pass
    return fontpaths