my %artists = (
    'Judas Priest' => ['Breaking the Law', 'Painkiller', 'Ram it Down'],
    'Iron Maiden' => ['Number of the Beast', 'Brave New World'],
    'Metallica' => ['Master of Puppets', 'One', 'Creeping Death']
);
for my $artist ( keys %artists ) {
    for my $song ( @{ $artists{$artist} } ) {
        print "$artist: $song\n";
    }
}