public function handle($old, $new)
    {
        if ( ! $this->canHandle($old) || ! $this->canHandle($new)) {
            return null;
        }

        if (((string) $new->getReturnType())) {
            return false;
        }

        if (((string) $new->getReturnType()) == ((string) $old->getReturnType())) {
            return false;
        }

        $this->lastException = new FailedConstraint(
            sprintf(
                '%s::%s() return type "%s" were removed',
                $old->getAttribute('parent')->namespacedName,
                $old->name,
                $old->getReturnType(),
                $new->getReturnType()
            )
        );

        return true;
    }