public function increment($metrics, $delta = 1, $sampleRate = 1, array $tags = [])
    {
        $metrics = (array) $metrics;
        $data = array();
        if ($sampleRate < 1) {
            foreach ($metrics as $metric) {
                if ((mt_rand() / mt_getrandmax()) <= $sampleRate) {
                    $data[$metric] = $delta . '|c|@' . $sampleRate;
                }
            }
        } else {
            foreach ($metrics as $metric) {
                $data[$metric] = $delta . '|c';
            }
        }
        return $this->send($data, $tags);
    }