#!/usr/local/bin/perl
use Data::Dumper;
my $hash = { a => 21, b => 32, c => 43 };
my $array = [ 11,12,13,14];

foreach (1..3){
    perform_operationX();
    print_data();
}

cancel_last_operationX(2);

sub perform_operationX {
    my $letter = chr(97+ int rand(10));
    my $number = int rand(100);
    $hash->{$letter} = $number;
    shift @$array;
}

sub print_data{
    print Dumper($hash,$array);
}

sub cancel_last_operationX {
    my $number_of_operations =  shift;
    ......... UNDO CODE .............

}