public function save(string $key, $value, int $ttl = 60)
	{
		$key = $this->prefix . $key;

		$contents = [
			'time' => time(),
			'ttl'  => $ttl,
			'data' => $value,
		];

		if ($this->writeFile($this->path . $key, serialize($contents)))
		{
			chmod($this->path . $key, 0640);

			return true;
		}

		return false;
	}