src/HOL/Tools/Nitpick/nitpick_scope.ML

     fun is_complete facto =
       has_exact_card hol_ctxt facto finitizable_dataTs card_assigns T
     fun is_concrete facto =
       is_word_type T orelse
       (* FIXME: looks wrong other types than just functions might be
-         abstract. *)
+         abstract. "is_complete" is also suspicious. *)
       xs |> maps (binder_types o snd) |> maps binder_types
          |> forall (has_exact_card hol_ctxt facto finitizable_dataTs
                                    card_assigns)
     val complete = pair_from_fun is_complete
     val concrete = pair_from_fun is_concrete