hierarchicalizeWithIds ((Header level attr@(_,classes,_) title'):xs) = do
  lastnum <- S.get
  let lastnum' = take level lastnum
  let newnum = case length lastnum' of
                    x | "unnumbered" `elem` classes -> []
                      | x >= level -> init lastnum' ++ [last lastnum' + 1]
                      | otherwise -> lastnum ++
                           replicate (level - length lastnum - 1) 0 ++ [1]
  unless (null newnum) $ S.put newnum
  let (sectionContents, rest) = break (headerLtEq level) xs
  sectionContents' <- hierarchicalizeWithIds sectionContents
  rest' <- hierarchicalizeWithIds rest
  return $ Sec level newnum attr title' sectionContents' : rest'
hierarchicalizeWithIds ((Header level attr@(_,classes,_) title'):xs) = do
  lastnum <- S.get
  let lastnum' = take level lastnum
  let newnum = case length lastnum' of
                    x | "unnumbered" `elem` classes -> []
                      | x >= level -> init lastnum' ++ [last lastnum' + 1]
                      | otherwise -> lastnum ++
                           replicate (level - length lastnum - 1) 0 ++ [1]
  unless (null newnum) $ S.put newnum
  let (sectionContents, rest) = break (headerLtEq level) xs
  sectionContents' <- hierarchicalizeWithIds sectionContents
  rest' <- hierarchicalizeWithIds rest
  return $ Sec level newnum attr title' sectionContents' : rest'
hierarchicalizeWithIds ((Header level attr@(_,classes,_) title'):xs) = do
  lastnum <- S.get
  let lastnum' = take level lastnum
  let newnum = case length lastnum' of
                    x | "unnumbered" `elem` classes -> []
                      | x >= level -> init lastnum' ++ [last lastnum' + 1]
                      | otherwise -> lastnum ++
                           replicate (level - length lastnum - 1) 0 ++ [1]
  unless (null newnum) $ S.put newnum
  let (sectionContents, rest) = break (headerLtEq level) xs
  sectionContents' <- hierarchicalizeWithIds sectionContents
  rest' <- hierarchicalizeWithIds rest
  return $ Sec level newnum attr title' sectionContents' : rest'