((output
  (((f.ml (1 0) (1 7))
    (5
     (label
      ((root (f.ml (page f.ml) 00000000000000000000000000000000) f.ml)
       (label foo)))
     (((f.ml (1 3) (1 6)) (word Foo)))))
   ((f.ml (2 0) (2 7))
    (5
     (label
      ((root (f.ml (page f.ml) 00000000000000000000000000000000) f.ml)
       (label bar)))
     (((f.ml (2 3) (2 6)) (word Bar)))))))
 (warnings
  ( "File \"f.ml\", line 2, characters 0-7:\
   \n'6': bad heading level (0-5 allowed).")))
