public function getBucket($bucketName = null, $password = null)
    {
        if ($bucketName === null) {
            $bucketName = $this->defaultBucket;
        }

        if (!array_key_exists($bucketName, $this->_buckets)) {
            $this->_buckets[$bucketName] = $this->selectBucket($bucketName, $password);
        }

        return $this->_buckets[$bucketName];
    }