((output
  (((f.ml (1 0) (1 9))
    (paragraph
     (((f.ml (1 0) (1 9)) (emphasis (((f.ml (1 5) (1 8)) (word foo))))))))))
 (warnings
  ( "File \"f.ml\", line 1, characters 3-3:\
   \nIdentifier in reference should not be empty.")))
