public function remember($key, Closure $callback)
{
// If the item exists in the repository we will just return this immediately
// otherwise we will execute the given Closure and repository the result
// of that execution for the given number of minutes in storage.
if (!is_null($value = $this->get($key))) {
return $value;
}
$this->put($key, $value = $callback());
return $value;
}