anchor.diff:                                 | {error, invalid_time}.
   format(Format, Datetime, Type) ->
       case Type of
  -        timestamp -> format_timestamp(Format, Datetime);
  -        now       -> format_now(Format, Datetime);
  -        datetime  -> format_datetime(Format, Datetime)
  +        unix     -> format_unix(Format, Datetime);
  +        now      -> format_now(Format, Datetime);
  +        datetime -> format_datetime(Format, Datetime)
       end.
   
   %% @doc Helper function similar to format/3.
   %%      @equiv format(Format, Datetime, timestamp)
   %% @end
  --spec format_timestamp(format(), unix_timestamp()) -> {ok, binary()}
  -                                                    | {error, invalid_time}.
  -format_timestamp(Format, Timestamp) ->
  +-spec format_unix(format(), unix_timestamp()) -> {ok, binary()}
  +                                               | {error, invalid_time}.
  +format_unix(Format, Timestamp) ->
       strftime(convert_format(Format), Timestamp).
   
   %% @doc Helper function similar to format/3.
  
positive.code:                                                 | {error, invalid_time}.
  format_now(Format, {MegaSecs, Secs, _MicroSecs}) ->
      Timestamp = ?M * MegaSecs + Secs,
      format_timestamp(Format, Timestamp).
  
  %% @doc Helper function similar to format/3.
  %%      @equiv format(Format, Datetime, datetime)
  
negative.code:                                                 | {error, invalid_time}.
  format_datetime(Format, Datetime) ->
      Timestamp = ?c:datetime_to_gregorian_seconds(Datetime) - ?EPOCH_ZERO,
      format_unix(Format, Timestamp).
  
  %% @private
  %% @doc Handles "format atoms" so standard formats will be handier to use.
  