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: 
  %% Ugly reformatting code to get times like +0000 and -1300
  
  -spec zone(float()) -> string().
  zone(Val) when Val < 0 ->
      io_lib:format("-~4..0w", [trunc(abs(Val))]);
  zone(Val) when Val >= 0 ->
  