public function updateStats($key, $delta = 1, $sampleRate = 1, $metric = 'c')
    {
        if (!is_array($key)) {
            $key = array($key);
        }
        $data = array();
        foreach ($key as $stat) {
            $data[$stat] = "$delta|$metric";
        }
        $this->send($data, $sampleRate);
    }