#!/usr/bin/perl -w
use strict;
my ( $key, $value );
my %hash = (
    rat => "acggghhh",
    mat => "dhhdhdhdh",
);
$hash{rat} = "fhhfjfjj";
$hash{rat} = "dggdgdgdg";
while ( ( $key, $value ) = each %hash ) {
    print "$key and $value \n";
}