anchor.diff:      Filter = riak_kv_coverage_filter:build_filter(ItemFilter),
       BufferMod = riak_kv_fold_buffer,
   
  -    Buffer = BufferMod:new(BufferSize, result_fun(Sender)),
  +    Buffer = riak_kv_fold_buffer:new(BufferSize, result_fun(Sender)),
       FoldFun = fold_fun(buckets, BufferMod, Filter, undefined),
       FinishFun = finish_fun(BufferMod, Sender),
       {ok, Capabilities} = Mod:capabilities(ModState),
  
positive.code:     Filter = riak_kv_coverage_filter:build_filter(Bucket, ItemFilter, FilterVNode),
      BufferMod = riak_kv_fold_buffer,
      BufferSize = proplists:get_value(buffer_size, Opts0, DefaultBufSz),
      Buffer = BufferMod:new(BufferSize, ResultFun),
      Extras = fold_extras_keys(Index, Bucket),
      FoldFun = fold_fun(range_scan, BufferMod, Filter, Extras),
      FinishFun = finish_fun(BufferMod, Sender),
  
negative.code:             FoldFun = fold_fun(keys, BufferMod, Filter, Extras),
              ModFun = fold_keys
      end,
      Buffer = riak_kv_fold_buffer:new(BufferSize, BufferFun),
      FinishFun =
          fun(Buffer1) ->
                  riak_kv_fold_buffer:flush(Buffer1),
  