How do I parse the JSON Date Format in Perl?

How can I parse this date format that my web service is receiving in JSON format in Perl? I'd like to convert it to a DateTime object:

Date(1216647000000-0400)

I assumed it was milliseconds since the epoch along with a time zone offset but the dates are way off.

From stackoverflow

• The time is listed in milliseconds since the epoch. Divide by 1000 to get epoch seconds.

  Make sure this works with other cases you encounter:

  use DateTime;
  
  my $json_date = 'Date(1216647000000-0400)';
  if ($json_date =~ m{ \b (\d+) \b ([+-]\d\d\d\d\b)? }x ) {
      my ( $epoch_milliseconds, $timezone ) = ( $1, $2 );
      my $dt = DateTime->from_epoch( epoch => $epoch_milliseconds / 1000 );
      if ($time_zone) {
          $dt->set_time_zone($time_zone);
      }
      print $dt->datetime;
  }
  

  ysth : \b is redundant between \d+ and [+-]. I'd remove the 2nd & 3rd \b and add one at the end.