Illuminate\Support\Collection::keys PHP Method

    public function keys()
    {
        return new static(array_keys($this->items));
    }

 /**
  * @param bool $asArray
  * @return array|static
  **/
 public function getStoredUrls($asArray = false)
 {
     $keys = $this->lookups->keys();
     if ($asArray) {
         return $keys->toArray();
     } else {
         return $keys;
     }
 }