def valid_redditors(redditors, sub):
    """Return a verified list of valid Redditor instances.

    :param redditors: A list comprised of Redditor instances and/or strings
        that are to be verified as actual redditor accounts.
    :param sub: A Subreddit instance that the authenticated account has
        flair changing permission on.

    Note: Flair will be unset for all valid redditors in `redditors` on the
    subreddit `sub`. A valid redditor is defined as a redditor that is
    registered on reddit.

    """
    simplified = list(set(six.text_type(x).lower() for x in redditors))
    return [sub.reddit_session.get_redditor(simplified[i], fetch=False)
            for (i, resp) in enumerate(sub.set_flair_csv(
                ({'user': x, 'flair_text': x} for x in simplified)))
            if resp['ok']]
Return a verified list of valid Redditor instances.

    :param redditors: A list comprised of Redditor instances and/or strings
        that are to be verified as actual redditor accounts.
    :param sub: A Subreddit instance that the authenticated account has
        flair changing permission on.

    Note: Flair will be unset for all valid redditors in `redditors` on the
    subreddit `sub`. A valid redditor is defined as a redditor that is
    registered on reddit.

    
rtv/packages/praw/helpers.py