public function get($key)
    {
        if ($time = $this->fast->get($key)) {
            return $time;
        }

        return $this->slow->get($key);
    }
public function get($key)
    {
        if ($time = $this->fast->get($key)) {
            return $time;
        }

        return $this->slow->get($key);
    }
@param string $key

@return \DateTime|null