use strict;
use warnings;
use 5.010;
...

my $end = do {
    my $month_ago = DateTime->now->subtract( months => 1 );
    sprintf '%02d%02d', substr( $month_ago->year, -2 ), $month_ago->month;
...

sub parse_decimal {
...

use strict;
use warnings;
use Test::More;
...

use MooseX::Declare;

class Keyboard with MooseX::Getopt {
...

%zip = (
    '0812' => [  'ex090130.log' ],
    '0901' => [  'ex081205.log', 'ex081206.log', 'ex081207.log' ],
...

use strict;
use warnings;
use DateTime;
...