addToUDFM_C
  :: Uniquable key => (elt -> elt -> elt) -- old -> new -> result
  -> UniqDFM elt -- old
  -> key -> elt -- new
  -> UniqDFM elt -- result
addToUDFM_C f m k v = addToUDFM_Directly_C f m (getUnique k) v
addToUDFM_C
  :: Uniquable key => (elt -> elt -> elt) -- old -> new -> result
  -> UniqDFM elt -- old
  -> key -> elt -- new
  -> UniqDFM elt
addToUDFM_C f m k v = addToUDFM_Directly_C f m (getUnique k) v
addToUDFM_C f m k v = addToUDFM_Directly_C f m (getUnique k) v