anchor.diff:          end
       end, Acc0, L).
   
  +-spec choose_random(list(T)) -> T.
   choose_random(L) ->
       lists:nth(random:uniform(length(L)), L).
   
  -    
  
positive.code:         _ -> {error, file_exists}
      end.
  
  diskspace(Path) ->
      case lists:reverse(string:tokens(os:cmd(["df -k ", Path]), "\n\t ")) of
          [_, _, Free|_] ->
  
negative.code:     list_to_tuple([erlang:list_to_integer(X, 16) ||
          X <- string:tokens(lists:flatten(T), "-")]).
  
  -spec pack_objname(string(), timer:timestamp()) -> binary().
  pack_objname(Name, T) ->
      list_to_binary([Name, "$", timestamp(T)]).
  
  -spec unpack_objname(binary() | string()) -> {binary(), timer:timestamp()}.
  unpack_objname(Obj) when is_binary(Obj) ->
      unpack_objname(binary_to_list(Obj));
  unpack_objname(Obj) ->
      [Name, Tstamp] = string:tokens(Obj, "$"),
      {list_to_binary(Name), timestamp_to_time(Tstamp)}.
  
  -spec ensure_dir(string()) -> 'eof' | 'ok' | {'error', _} | {'ok', _}.
  ensure_dir(Dir) ->
      case prim_file:make_dir(Dir) of
          ok -> ok;
  