use DateTime;
    use DateTime::Format::ISO8601;

    my ($first, $last) = map { DateTime::Format::ISO8601->parse_datetime($_) }
                          qw < 2013-08-01T20:10:31 2013-08-06T20:09:34 >;

    my ($sub, $days) = map { $last->$_($first) }
                         qw< subtract_datetime delta_days >;

    printf "%12s   %5s | %-5s\n", 'Value', 'sub', 'days';
    printf "%.21s+%.8s\n", ('-'x21)x2;
    for (qw< months days minutes seconds nanoseconds >) {
        printf "%12s : %5d | %-5d\n", $_, $sub->{$_}, $days->{$_};
    }