#!/usr/bin/perl
use strict;
use warnings;
use NetAddr::IP;
use feature 'say';

say NetAddr::IP->new('127.0.0.1/8') + 255;
say NetAddr::IP->new('127.0.1.6/8') - 255;

__END__

$ perl test.pl
127.0.1.0/8
127.0.0.7/8