The code from `internalGetItem`:
```php
        $result = $memc->get($internalKey);
        $success = ($result !== false);
        if ($result === false) {
            return null;
        }
        $casToken = $result;
        return $result;
```
... so `FALSE` means that the item doesn't exist.

What is the result of the following ?:
```php
$cache->setItem('test', false);
var_dump($cache->getItem('test', $success));
var_dump($success);
```