public function close($reply_code = 0, $reply_text = '', $method_sig = array(0, 0))
    {
        $this->callbacks = array();
        if ($this->is_open === false || $this->connection === null) {
            $this->do_close();

            return null; // already closed
        }
        list($class_id, $method_id, $args) = $this->protocolWriter->channelClose(
            $reply_code,
            $reply_text,
            $method_sig[0],
            $method_sig[1]
        );

        try {
            $this->send_method_frame(array($class_id, $method_id), $args);
        } catch (\Exception $e) {
            $this->do_close();

            throw $e;
        }

        return $this->wait(array(
            $this->waitHelper->get_wait('channel.close_ok')
        ), false, $this->channel_rpc_timeout );
    }