anchor.diff:  
   %% @doc Return a four-tuple containing year, month, day, and hour
   %% of the current time.
  --type datehour() :: {calendar:year(), calendar:month(), calendar:day(), calendar:hour()}.
  +-type datehour() :: {non_neg_integer(), 1..12, 1..31, 0..23}.
   -spec datehour() -> datehour().
   datehour() ->
       datehour(os:timestamp()).
  
positive.code:          zeropad/2,
           zone/0]).
  
  -record(state, {hourstamp :: non_neg_integer(),
                  filename :: string(),
                  handle :: file:io_device()}).
  
  
negative.code: %% @doc Close a log file.
  -spec log_close(atom(), string(), file:io_device()) -> ok | {error, term()}.
  log_close(Mod, Name, FD) ->
      log_info([atom_to_list(Mod), ": closing log file: ", Name, $\n]),
      file:close(FD).
  
  %% @doc Notify registered log event handler of an error event.
  