public function isSubclassOf(CodeBase $code_base, Type $parent)
{
$fqsen = $this->asFQSEN();
assert($fqsen instanceof FullyQualifiedClassName);
$this_clazz = $code_base->getClassByFQSEN($fqsen);
$parent_fqsen = $parent->asFQSEN();
assert($parent_fqsen instanceof FullyQualifiedClassName);
$parent_clazz = $code_base->getClassByFQSEN($parent_fqsen);
return $this_clazz->isSubclassOf($code_base, $parent_clazz);
}