public function watch($keyOrKeys)
    {
        $this->_throwIfNotSupported('Watch', '2.1');

        $command = array('WATCH');

        if (!is_array($keyOrKeys)) {
            $keys = array($keyOrKeys);
        } else {
            $keys = $keyOrKeys;
        }

        foreach($keys as $key) {
            $command[] = $this->_rediska->getOption('namespace') . $key;
        }

        $exec = new Rediska_Connection_Exec($this->_connection, $command);
        $exec->execute();

        $this->_isWatched = true;

        return $this;
    }