import praw

SUB = "somesub" # subreddit to watch for comments
TO_SKIP = ['HappySilveon', 'AutoModerator'] # list of users to ignore
SUBJECT = "Some subject" # required subject for the PM
REPLY = "PM content here." # The content of the PM we'll respond with


def main():
    reddit = praw.Reddit(user_agent='/u/HappySilveon reply script',
                         client_id='CLIENT_ID', client_secret='CLIENT_SECRET',
                         username='USERNAME', password='PASSWORD')
    sub = reddit.subreddit(SUB)
    for cmt in sub.stream.comments(skip_existing=True):
        user = str(cmt.author)
        if user not in TO_SKIP:
            reddit.redditor(user).message(SUBJECT, REPLY)


if __name__ == '__main__':
    main()