anchor.diff:        Acc1 :: term(),
         AccIn :: term(),
         AccOut :: term(),
  -      Abstr :: erl_parse_tree().
  +      Abstr :: erl_parse_tree() | form_info().
   
   fold_anno(F0, Acc0, Abstr) ->
       F = fun(A, Acc) -> {A, F0(A, Acc)} end,
  
positive.code:       Fun :: fun((Anno) -> NewAnno),
        Anno :: erl_anno:anno(),
        NewAnno :: erl_anno:anno(),
        Abstr :: erl_parse_tree(),
        NewAbstr :: erl_parse_tree().
  
  map_anno(F0, Abstr) ->
      F = fun(A, Acc) -> {F0(A), Acc} end,
  
negative.code:       Acc1 :: term(),
        AccIn :: term(),
        AccOut :: term(),
        Abstr :: erl_parse_tree() | form_info(),
        NewAbstr :: erl_parse_tree() | form_info().
  
  mapfold_anno(F, Acc0, Abstr) ->
      modify_anno1(Abstr, Acc0, F).
  
  -spec new_anno(Term) -> Abstr when
        Term :: term(),
        Abstr :: erl_parse_tree() | form_info().
  
  new_anno(Term) ->
      F = fun(L, Acc) -> {erl_anno:new(L), Acc} end,
  