package Classes::SomeParent;
1;
package Classes::SomeChild;
our @ISA=("Classes::SomeParent");
package main;

my $class = 'Classes::SomeChild;
my $obj = {};
bless $obj, 'Classes::SomeChild';
if ($obj->isa('Classes::SomeParent')) {
    print "Isa";
} else {
    print "Nota";
}

##</code><code>##

print "Object is ". (is_tainted($obj) ? "not " : "") . "tainted";