9. Generic dereferencing syntax 

my @array = ( 'Tom', 'Dick', 'Larry' );
my %hash  = ( 'I' => 1, 'II' => 2, 'III' => 3 );

say $array[2];
say $hash{III};

# Anywhere you might use an array or a hash you can
# replace the identifier with curly braces containing
# an expression which returns an arrayref or hashref:

say ${$arrayref}[2];
say ${$hashref}{III};