{
    package Null;
    use overload
        bool => sub { undef },
        '""' => sub { undef },
        '0+' => sub { undef },
        fallback => 1,
        nomethod => 'AUTOLOAD';

    sub AUTOLOAD { return; }
}

{
    package Foo;
    sub new { return bless { a => 'b' }, shift; }
    sub apple { 'pear' }
}

my %x = (
    foo => Foo->new,
);
my $y = $x{foo};
print "Y1: $y\n";

bless $x{foo}, 'Null';
%{$x{foo}} = ();

print "Y2: $y\n";
my $z = $x{foo};
print "Z: $z\n";