use strict;
use warnings;

warn "version $]";

my %hash=(a=>undef,b=>[]);
my $h=\%hash;

my @array=({a=>undef});
my $a=\@array;


warn "hash $hash{a}";
warn "hoa $hash{b}[0]";

warn "hashref $h->{a}";
warn "hoa ref $h->{b}[0]";

warn "array $array[1] ";
warn "aoh $array[0]{a} ";

warn "array ref $a->[1] ";
warn "aoh   ref $a->[0]{a} ";