public function append($key, $value, $expiration = 0, $flags = self::FLAG_DEFAULT, $bytes = null)
    {
        /**
         * replace <key> <flags> <exptime> <bytes> [noreply]\r\n
         * <value>\r\n
         */

        // Calculate bytes if not precalculated
        $bytes = ($bytes !== null) ? $bytes : strlen($value);

        // Build packet to send ...
        $data = self::COMMAND_APPEND . self::COMMAND_SEPARATOR   .
            $key                     . self::COMMAND_SEPARATOR   .
            $flags                   . self::COMMAND_SEPARATOR   .
            $expiration              . self::COMMAND_SEPARATOR   .
            $bytes                   . self::COMMAND_TERMINATOR  .
            $value                   . self::COMMAND_TERMINATOR;

        return $this->send(self::COMMAND_APPEND, $data);
    }