public function dropRight($num)
    {
        return $num !== $this->count()
            ? $this->slice(0, $this->count() - $num - 1)
            : $this->clear();
    }
public function dropRight($num)
    {
        return $num !== $this->count()
            ? $this->slice(0, $this->count() - $num - 1)
            : $this->clear();
    }
{@inheritdoc}