use Data::Dumper;

$hash{a} = [ 1, 2, 3 ];
$hash{b} = [ 4, 5, 6 ];

print Dumper(\%hash);

while (($key, $value) = each %hash) {
    print $key, "\n";
    delete $hash{$key};
}

##</code><code>##

$VAR1 = {
          'a' => [
                   1,
                   2,
                   3
                 ],
          'b' => [
                   4,
                   5,
                   6
                 ]
        };
a
b