protected function _throwExceptionIfNotSupported($version = null)
    {
        if (null === $version) {
            $version = $this->_version;
        }

        $redisVersion = $this->_rediska->getOption('redisVersion');

        if (version_compare($version, $redisVersion) == 1) {
            throw new Rediska_Command_Exception("Command '{$this->_name}' requires {$version}+ version of Redis server. Current version is {$redisVersion}. To change it specify 'redisVersion' option.");
        }
    }