#!/usr/bin/env perl
use warnings;
use strict;
no autovivification qw{fetch store exists delete}; 

my $h = { a => { p => 2, q => 3 } };

print "perl ver $], autoviv ver $autovivification::VERSION:\n"; 
! $$h{a}{x}{z} and print "a/x/z not\n"; 

__END__

perl ver 5.024004, autoviv ver 0.16:
a/x/z not

perl ver 5.028001, autoviv ver 0.16:
a/x/z not

perl ver 5.024004, autoviv ver 0.18:
Can't vivify reference at a.pl line 9.

perl ver 5.028001, autoviv ver 0.18:
Can't vivify reference at a.pl line 9.