use strict;
use warnings;
my %list=("bob" =>123,
          "tom" => "CAT");
sub change(\%){
    my $temp = shift;
    foreach (keys %$temp){
        print $_. " = $$temp{$_}\n";
        $$temp{$_} .= "hello";
    }
}
change (%list);
foreach (keys %list){
    print "$_ = $list{$_}\n";
}