/**
* Sort the array using the given callback.
*
* @param array $array
* @param callable $callback
*
* @return array
*/
public static function sort($array, callable $callback)
{
return Collection::make($array)->sortBy($callback)->all();
}
/**
* Fetches the data item keys from the persistent data storage.
*
* @return array list of data item keys.
*/
protected function fetchKeys()
{
return $this->collection->first() instanceof Fluent ? array_keys($this->collection->first()->attributes()) : array();
}