private function clearExpiredKey($key, DateTime $dateTime)
    {
        if (self::$registry[$key]['expires'] < $dateTime) {
            unset(self::$registry[$key]);
        }
    }
private function clearExpiredKey($key, DateTime $dateTime)
    {
        if (self::$registry[$key]['expires'] < $dateTime) {
            unset(self::$registry[$key]);
        }
    }
private function clearExpiredKey ( $ key , DateTime $ dateTime ) { if ( self :: $ registry [ $ key ] [ 'expires' ] < $ dateTime ) { unset ( self :: $ registry [ $ key ] ) ; } }
Clear an item if it expired.

@param          $key
@param DateTime $dateTime
Clear an item if it expired .