my $hr = undef;
$hr->{radish} = "crunch";       # yes autoviv
$hr->{banana} = "squish";       # no  autoviv

my @a = ("a" .. "z");
$a[0][1] = "new level";         # yes autoviv
$a[0][9] = "new element";       # no  autoviv

my %h = ( );
$h{little}{dog}  = "puppy" ;    # yes autoviv
$h{little}{cat}  = "kitten";    # no  autoviv
$h{male}{cattle} = "bull";      # yes autoviv
$h{male}{cat}    = "tom";       # no  autoviv