use DateTime;
use DateTime::Duration;
use DateTime::Format::DateParse;

my $dt_now = DateTime::Format::DateParse->parse_datetime("2010-01-29T08:00:00 UTC");
my $dt_then = DateTime::Format::DateParse->parse_datetime("2010-01-29T06:00:00 UTC");
print "subtract localtime $dt_now $dt_then\n";
my $dt_duration = $dt_then - $dt_now;
print $dt_duration->is_positive."\n";
print $dt_duration->hours()."\n";