anchor.diff:  map__lookup(Key, Map) ->
     try dict:fetch(Key, Map) catch error:_ -> none end.
   
  --spec map__from_list([{term(), term()}]) -> map().
  +-spec map__from_list([{fa(), term()}]) -> map().
   map__from_list(List) ->
     dict:from_list(List).
   
  
positive.code: map__remove(Key, Dict) ->
    dict:erase(Key, Dict).
  
  -spec map__fold(fun((term(), term(), term()) -> term()), term(), map()) -> term().
  map__fold(Fun, Acc0, Dict) -> 
    dict:fold(Fun, Acc0, Dict).
  
negative.code: 
  %%--------------------------------------------------------------------
  %% A convenient abstraction of a Key-Value mapping data structure
  %% specialized for the uses in this module
  %%--------------------------------------------------------------------
  
  -type map() :: dict().
  