anchor.diff:      end.
   
   do_get_from_json(Key, JSON) ->
  -    {_, Lens, _} = lists:keyfind(Key, 1, known_settings()),
  +    {_, Lens} = lists:keyfind(Key, 1, known_settings()),
       Settings = decode_settings_json(JSON),
       lens_get(Lens, Settings).
   
  
positive.code: compaction_lens() ->
      {fun compaction_lens_get/1, fun compaction_lens_set/2}.
  
  compaction_defaults() ->
      [{Key, Default} || {Key, _, Default} <- compaction_lens_props()].
  
  lens_get({Get, _}, Dict) ->
      Get(Dict).
  
  lens_get_many(Lenses, Dict) ->
      [{Key, lens_get(L, Dict)} || {Key, L, _} <- Lenses].
  
  lens_set(Value, {_, Set}, Dict) ->
      Set(Value, Dict).
  
negative.code: 
  general_settings_lens() ->
      {fun general_settings_lens_get/1, fun general_settings_lens_set/2}.
  
  compaction_interval_default() ->
      [{from_hour, 0},
  