/**
* @param string $key
* @param callable|null $callback
* @return string
*/
public function get($key, $callback = null)
{
$value = $this->connector->get($key);
if (is_null($value)) {
$callback = $this->getCallback($callback);
$value = $callback($key);
if (!is_null($value)) {
$this->connector->set($key, $value);
}
}
return $value;
}
