anchor.diff:  
   fold_it(Fun, Acc, It) ->
       case itr_done(It) of
  -        true -> Acc;
  +        true ->
  +            ok = itr_close(It),
  +            Acc;
           false ->
               Next = Fun(itr_key_values(It), Acc),
               fold_it(Fun, Next, itr_next(It))
  
positive.code:             maybe_tombstone(maybe_resolve(PKey, Existing, ResolveMethod), Default)
      end.
  
  %% @spec same as fold(Fun, Acc0, FullPrefix, []).
  -spec fold(fun(({metadata_key(),
                   [metadata_value() | metadata_tombstone()] |
                   metadata_value() | metadata_tombstone()}, any()) -> any()),
  
negative.code: fold(Fun, Acc0, FullPrefix) ->
      fold(Fun, Acc0, FullPrefix, []).
  
  %% @doc Fold over all keys and values stored under a given prefix/subprefix. Available
  %% options are the same as those provided to iterator/2.
  -spec fold(fun(({metadata_key(),
                   [metadata_value() | metadata_tombstone()] |
  