collectHeaders :: Block -> [Block]
collectHeaders header@(Header _ (_, classes, _) _)
  | "notoc" `elem` classes = []
  | otherwise              = [header]
collectHeaders :: Block -> [Block]
collectHeaders header@(Header _ (_, classes, _) _)
  | "notoc" `elem` classes = []
  | otherwise              = [header]
collectHeaders header@(Header _ (_, classes, _) _)
  | "notoc" `elem` classes = []
  | otherwise              = [header]