 | Get the CommentId this CommentId was rethreaded to, if it was.
fetchCommentRethreadDB :: CommentId -> DB (Maybe CommentId)
fetchCommentRethreadDB comment_id = fmap unValue . listToMaybe <$> (
    select $
    from $ \cr -> do
    where_ $ cr ^. CommentRethreadOldComment ==. val comment_id
    return $ cr ^. CommentRethreadNewComment)


fetchCommentRethreadDB :: CommentId -> DB (Maybe CommentId)
fetchCommentRethreadDB comment_id = fmap unValue . listToMaybe <$> (
    select $
    from $ \cr -> do
    where_ $ cr ^. CommentRethreadOldComment ==. val comment_id
    return $ cr ^. CommentRethreadNewComment)
fetchCommentRethreadDB comment_id = fmap unValue . listToMaybe <$> (
    select $
    from $ \cr -> do
    where_ $ cr ^. CommentRethreadOldComment ==. val comment_id
    return $ cr ^. CommentRethreadNewComment)