Invalid append 1
$VAR1 = 1;
$VAR1 = 2;
$VAR1 = 3;
$VAR1 = 'foo';
$VAR1 = 'bar';
$VAR1 = 'baz';
$VAR1 = sub {
            use warnings;
            use strict 'refs';
            return $start <= $end ? $start++ : undef;
        };